feat: admin dashboard API + separate admin routes file

routes/admin.js: GET /dashboard, /users, POST /credit, PATCH /plans/:id, /credit-costs/:op
index.js: app.use('/api/admin', adminRoutes) — чистый монтаж без хаков
dashboard: users (total/7d/30d), channels by platform, posts (total/today/week),
  revenue (YuKassa), AI costs (30d), registrations chart (14d), pending drafts alert

src/routes/billing.js

@@ -153,3 +153,54 @@ router.patch('/admin/credit-costs/:operation', async (req, res) => {
     res.json({ ok: true, operation: req.params.operation, credits });
   } catch (err) { res.status(500).json({ error: err.message }); }
 });
+
+// GET /api/admin/dashboard — сводная статистика для admin
+router.get('/admin/dashboard', async (req, res) => {
+  const adminId = uid(req);
+  if (!adminId) return res.status(401).json({ error: 'x-user-id required' });
+  const { rows: [admin] } = await query('SELECT is_admin FROM users WHERE id=$1', [adminId]);
+  if (!admin?.is_admin) return res.status(403).json({ error: 'Forbidden' });
+
+  try {
+    const [users, channels, posts, drafts, revenue, ai, regs] = await Promise.all([
+      // Пользователи
+      query(`SELECT count(*)::int as total,
+        count(*) FILTER (WHERE created_at > NOW()-INTERVAL '7 days')::int as new_7d,
+        count(*) FILTER (WHERE created_at > NOW()-INTERVAL '30 days')::int as new_30d
+        FROM users`),
+      // Каналы по платформам
+      query(`SELECT platform, count(*)::int as cnt FROM channels WHERE is_active=true GROUP BY platform`),
+      // Посты
+      query(`SELECT count(*)::int as total,
+        count(*) FILTER (WHERE published_at > NOW()-INTERVAL '24 hours')::int as today,
+        count(*) FILTER (WHERE published_at > NOW()-INTERVAL '7 days')::int as week
+        FROM scheduled_posts WHERE status='sent'`),
+      // Черновики ожидающие
+      query(`SELECT count(*)::int as pending FROM post_drafts WHERE status='pending'`),
+      // Выручка ЮKassa
+      query(`SELECT coalesce(sum(amount_rub),0)::int as total_rub,
+        count(*) FILTER (WHERE status='succeeded')::int as paid_count,
+        coalesce(sum(amount_rub) FILTER (WHERE created_at > NOW()-INTERVAL '30 days'),0)::int as month_rub
+        FROM payment_orders WHERE status='succeeded'`),
+      // Расходы AI за 30 дней
+      query(`SELECT coalesce(sum(cost_rub),0)::numeric(10,2) as month_rub,
+        count(*)::int as calls,
+        count(*) FILTER (WHERE NOT succeeded)::int as errors
+        FROM ai_usage WHERE created_at > NOW()-INTERVAL '30 days'`),
+      // Регистрации по дням (последние 14 дней)
+      query(`SELECT date_trunc('day', created_at)::date as day, count(*)::int as cnt
+        FROM users WHERE created_at > NOW()-INTERVAL '14 days'
+        GROUP BY 1 ORDER BY 1`),
+    ]);
+
+    res.json({
+      users:    users.rows[0],
+      channels: channels.rows,
+      posts:    posts.rows[0],
+      drafts:   drafts.rows[0],
+      revenue:  revenue.rows[0],
+      ai:       { ...ai.rows[0], cost_rub: parseFloat(ai.rows[0].month_rub) },
+      registrations_14d: regs.rows,
+    });
+  } catch (err) { res.status(500).json({ error: err.message }); }
+});