feat: promo codes UI + apply on /billing

AdminPromos.js: создание/список/toggle/удаление промокодов
  auto-generated code, type (credits/%), max_uses, expires, description
AdminPanel: раздел Промокоды между Тарифами и Пользователями
/billing page: кнопка '🎁 Есть промокод?' → форма ввода → apply-promo API
API routes: /api/admin/promos, /api/admin/promos/[id], /api/billing/apply-promo

components/AdminPanel.js

@@ -1,9 +1,10 @@
 'use client';
 import { useState } from 'react';
-import { Settings2, CreditCard, TrendingUp, Users, ChevronRight, Loader2, Eye, EyeOff, Save, RefreshCw, Check, AlertCircle, BarChart3, ArrowLeft, Zap } from 'lucide-react';
+import { Settings2, CreditCard, TrendingUp, Users, ChevronRight, Loader2, Eye, EyeOff, Save, RefreshCw, Check, AlertCircle, BarChart3, ArrowLeft, Zap, Tag } from 'lucide-react';
 import Link from 'next/link';
 import AdminBilling from './admin/AdminBilling';
 import AdminUsers  from './admin/AdminUsers';
+import AdminPromos from './admin/AdminPromos';
 
 // ──────────────────────────────────────────────────────────────
 // Sidebar navigation
@@ -15,6 +16,7 @@ const SECTIONS = [
   { id: 'payments',  label: 'ЮKassa',          icon: CreditCard, desc: 'Ключи для приёма оплат' },
   { id: 'spending',  label: 'Расходы AI',       icon: TrendingUp, desc: 'aiprimetech + routerai' },
   { id: 'plans',     label: 'Тарифы',           icon: BarChart3,  desc: 'Планы, кредиты, операции' },
+  { id: 'promos',    label: 'Промокоды',         icon: Tag,         desc: 'Коды для кредитов и скидок' },
   { id: 'billing',   label: 'Пользователи',     icon: Users,      desc: 'Балансы и кредиты' },
 ];
 
@@ -64,6 +66,7 @@ export default function AdminPanel({ initialSection = 'settings' }) {
           {section === 'payments' && <SettingsSection categories={['payments']} />}
           {section === 'spending' && <SpendingSection />}
           {section === 'plans'    && <PlansSection />}
+          {section === 'promos'   && <AdminPromos />}
           {section === 'billing'  && <AdminUsers />}
         </div>
       </div>

components/admin/AdminPromos.js

@@ -0,0 +1,222 @@
+'use client';
+import { useState, useEffect } from 'react';
+import { Plus, Trash2, RefreshCw, Loader2, Check, Copy, Tag, ToggleLeft, ToggleRight } from 'lucide-react';
+
+function randomCode() {
+  const chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
+  return Array.from({length:8}, () => chars[Math.floor(Math.random()*chars.length)]).join('');
+}
+
+function fmtDate(s) {
+  if (!s) return '∞';
+  return new Date(s).toLocaleDateString('ru-RU');
+}
+
+export default function AdminPromos() {
+  const [promos,  setPromos]  = useState([]);
+  const [loading, setLoading] = useState(true);
+  const [saving,  setSaving]  = useState(false);
+  const [msg,     setMsg]     = useState('');
+  const [showForm,setShowForm]= useState(false);
+
+  // Form
+  const [code,      setCode]     = useState(randomCode());
+  const [type,      setType]     = useState('credits');
+  const [value,     setValue]    = useState('100');
+  const [maxUses,   setMaxUses]  = useState('1');
+  const [expiresAt, setExpiresAt]= useState('');
+  const [desc,      setDesc]     = useState('');
+
+  async function load() {
+    setLoading(true);
+    try {
+      const res = await fetch('/api/admin/promos').then(r => r.json());
+      setPromos(Array.isArray(res) ? res : []);
+    } catch {}
+    setLoading(false);
+  }
+
+  useEffect(() => { load(); }, []);
+
+  async function create() {
+    if (!code || !value) return;
+    setSaving(true);
+    try {
+      const res = await fetch('/api/admin/promos', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          code, type, value: parseInt(value),
+          max_uses: parseInt(maxUses) || 1,
+          expires_at: expiresAt || null,
+          description: desc || null,
+        }),
+      }).then(r => r.json());
+      if (res.error) { setMsg('Ошибка: ' + res.error); }
+      else {
+        setMsg('Промокод создан ✓');
+        setShowForm(false);
+        setCode(randomCode());
+        setValue('100'); setMaxUses('1'); setExpiresAt(''); setDesc('');
+        load();
+      }
+    } catch { setMsg('Ошибка соединения'); }
+    setSaving(false);
+    setTimeout(() => setMsg(''), 3000);
+  }
+
+  async function toggleActive(promo) {
+    await fetch(`/api/admin/promos/${promo.id}`, {
+      method: 'PATCH',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ is_active: !promo.is_active }),
+    });
+    load();
+  }
+
+  async function deletePromo(id) {
+    if (!confirm('Удалить промокод?')) return;
+    await fetch(`/api/admin/promos/${id}`, { method: 'DELETE' });
+    load();
+  }
+
+  function copyCode(code) {
+    navigator.clipboard.writeText(code).catch(() => {});
+    setMsg('Скопировано: ' + code);
+    setTimeout(() => setMsg(''), 2000);
+  }
+
+  const TYPE_LABELS = { credits: '🎁 Кредиты', discount_pct: '% Скидка' };
+
+  return (
+    <div className="space-y-5">
+      <div className="flex items-center justify-between">
+        <h2 className="font-semibold">Промокоды</h2>
+        <div className="flex gap-2">
+          {msg && <span className="text-sm text-green-400 self-center">{msg}</span>}
+          <button onClick={() => load()} className="btn-ghost p-2"><RefreshCw className="w-4 h-4" /></button>
+          <button onClick={() => setShowForm(v => !v)} className="btn-primary text-sm px-3 py-1.5 flex items-center gap-1.5">
+            <Plus className="w-4 h-4" /> Создать
+          </button>
+        </div>
+      </div>
+
+      {/* Форма создания */}
+      {showForm && (
+        <div className="card p-5 border-accent/30 bg-accent/5 space-y-4">
+          <h3 className="font-medium text-sm">Новый промокод</h3>
+          <div className="grid grid-cols-2 gap-3">
+            <div>
+              <label className="label text-xs mb-1">Код</label>
+              <div className="flex gap-1">
+                <input value={code} onChange={e => setCode(e.target.value.toUpperCase())}
+                  className="input flex-1 font-mono text-sm py-1.5" maxLength={32} />
+                <button onClick={() => setCode(randomCode())} className="btn-ghost p-2 text-xs" title="Генерировать">↻</button>
+              </div>
+            </div>
+            <div>
+              <label className="label text-xs mb-1">Тип</label>
+              <select value={type} onChange={e => setType(e.target.value)} className="input w-full text-sm py-1.5">
+                <option value="credits">🎁 Бонусные кредиты</option>
+                <option value="discount_pct">% Скидка на подписку</option>
+              </select>
+            </div>
+            <div>
+              <label className="label text-xs mb-1">{type === 'credits' ? 'Кредитов' : 'Скидка %'}</label>
+              <input type="number" value={value} onChange={e => setValue(e.target.value)}
+                className="input w-full text-sm py-1.5" min={1} max={type === 'discount_pct' ? 100 : 10000} />
+            </div>
+            <div>
+              <label className="label text-xs mb-1">Макс. использований (-1 = ∞)</label>
+              <input type="number" value={maxUses} onChange={e => setMaxUses(e.target.value)}
+                className="input w-full text-sm py-1.5" min={-1} />
+            </div>
+            <div>
+              <label className="label text-xs mb-1">Истекает (необязательно)</label>
+              <input type="date" value={expiresAt} onChange={e => setExpiresAt(e.target.value)}
+                className="input w-full text-sm py-1.5" />
+            </div>
+            <div>
+              <label className="label text-xs mb-1">Описание</label>
+              <input value={desc} onChange={e => setDesc(e.target.value)}
+                placeholder="Для партнёров..." className="input w-full text-sm py-1.5" />
+            </div>
+          </div>
+          <div className="flex gap-2">
+            <button onClick={create} disabled={saving || !code || !value}
+              className="btn-primary px-4 py-2 text-sm flex items-center gap-1.5">
+              {saving ? <Loader2 className="w-4 h-4 animate-spin" /> : <Check className="w-4 h-4" />}
+              Создать
+            </button>
+            <button onClick={() => setShowForm(false)} className="btn-ghost px-4 py-2 text-sm">Отмена</button>
+          </div>
+        </div>
+      )}
+
+      {/* Список */}
+      {loading && <div className="py-8 text-center"><Loader2 className="w-5 h-5 animate-spin mx-auto text-accent" /></div>}
+
+      {!loading && promos.length === 0 && (
+        <div className="py-12 text-center text-gray-500 text-sm">
+          <Tag className="w-10 h-10 mx-auto mb-3 opacity-20" />
+          Промокодов пока нет
+        </div>
+      )}
+
+      {!loading && promos.length > 0 && (
+        <div className="card overflow-hidden">
+          <table className="w-full text-sm">
+            <thead className="bg-surface2 text-xs text-gray-400">
+              <tr>
+                <th className="px-4 py-2.5 text-left">Код</th>
+                <th className="px-4 py-2.5 text-center">Тип / Ценность</th>
+                <th className="px-4 py-2.5 text-center">Использован</th>
+                <th className="px-4 py-2.5 text-center">Истекает</th>
+                <th className="px-4 py-2.5 text-center">Статус</th>
+                <th className="px-4 py-2.5 text-center">Действия</th>
+              </tr>
+            </thead>
+            <tbody>
+              {promos.map(p => (
+                <tr key={p.id} className={`border-t border-border ${!p.is_active ? 'opacity-50' : ''} hover:bg-surface2/50`}>
+                  <td className="px-4 py-2.5">
+                    <div className="flex items-center gap-2">
+                      <code className="font-mono font-bold text-accent">{p.code}</code>
+                      <button onClick={() => copyCode(p.code)} className="btn-ghost p-1" title="Скопировать">
+                        <Copy className="w-3 h-3" />
+                      </button>
+                    </div>
+                    {p.description && <div className="text-xs text-gray-500 mt-0.5">{p.description}</div>}
+                  </td>
+                  <td className="px-4 py-2.5 text-center">
+                    <div className="text-xs text-gray-400">{TYPE_LABELS[p.type]}</div>
+                    <div className="font-bold">{p.type === 'credits' ? `+${p.value} кр` : `${p.value}%`}</div>
+                  </td>
+                  <td className="px-4 py-2.5 text-center">
+                    <span className={p.uses_real >= p.max_uses && p.max_uses !== -1 ? 'text-red-400' : ''}>
+                      {p.uses_real} / {p.max_uses === -1 ? '∞' : p.max_uses}
+                    </span>
+                  </td>
+                  <td className="px-4 py-2.5 text-center text-xs text-gray-400">{fmtDate(p.expires_at)}</td>
+                  <td className="px-4 py-2.5 text-center">
+                    <button onClick={() => toggleActive(p)}>
+                      {p.is_active
+                        ? <ToggleRight className="w-5 h-5 text-green-400 mx-auto" />
+                        : <ToggleLeft className="w-5 h-5 text-gray-500 mx-auto" />}
+                    </button>
+                  </td>
+                  <td className="px-4 py-2.5 text-center">
+                    <button onClick={() => deletePromo(p.id)}
+                      className="btn-ghost p-1.5 text-gray-500 hover:text-red-400 mx-auto">
+                      <Trash2 className="w-3.5 h-3.5" />
+                    </button>
+                  </td>
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+      )}
+    </div>
+  );
+}