feat: billing system — credits, plans, transactions

DB:
- plans: free/starter/pro/business с ценами и лимитами
- user_subscriptions: подписка пользователя на план
- user_balance: баланс кредитов + monthly reset
- user_transactions: история всех движений кредитов
- credit_costs: image=5, text_post=2, article=5, autopublish=0

Engine:
- services/billing.js: getBalance, check, spend, credit, getTransactions, processMonthlyResets
- routes/billing.js: GET /balance, /transactions, /plans, POST /admin/credit, GET /admin/users
- routes/generate.js: списание кредитов перед генерацией (text_post, article, image)
- index.js: GET /api/billing/plans публично (без auth)

src/routes/generate.js

@@ -3,18 +3,33 @@ const router = express.Router();
 const { query } = require('../config/db');
 const channelsSvc = require('../services/channels');
 const generationQueue = require('../workers/generation');
+const billing = require('../services/billing');
+
+// Маппинг type → billing operation
+const BILLING_OP = { post: 'text_post', article: 'article', topics: null };
 
 // POST /api/generate — создать задачу генерации
 router.post('/', async (req, res) => {
   try {
     const { type, topic, channelId, rubric, keywords = [], useCritique = true, customPrompt } = req.body;
-    const userId = req.headers['x-user-id'] || null;
+    const userId = req.headers['x-user-id'] ? parseInt(req.headers['x-user-id']) : null;
 
     if (!type) return res.status(400).json({ error: 'type is required' });
     if (!['post', 'article', 'topics'].includes(type)) return res.status(400).json({ error: 'Invalid type' });
     if (type !== 'topics' && !topic) return res.status(400).json({ error: 'topic is required' });
     if (type === 'post' && !channelId) return res.status(400).json({ error: 'channelId is required for posts' });
 
+    // Проверка и списание кредитов
+    const billingOp = BILLING_OP[type];
+    let billingResult = null;
+    if (userId && billingOp) {
+      const ck = await billing.check(userId, billingOp);
+      if (!ck.allowed) {
+        return res.status(402).json({ error: ck.reason, code: 'INSUFFICIENT_CREDITS', credits: ck.credits, cost: ck.cost });
+      }
+      billingResult = await billing.spend(userId, billingOp, { channel_id: channelId });
+    }
+
     const { rows } = await query(
       `INSERT INTO generation_jobs (user_id, channel_id, type, topic, rubric, status)
        VALUES ($1,$2,$3,$4,$5,'pending') RETURNING id`,
@@ -24,7 +39,7 @@ router.post('/', async (req, res) => {
 
     await generationQueue.add({ jobId, type, topic, channelId, rubric, keywords, useCritique, customPrompt });
 
-    res.json({ jobId, status: 'pending' });
+    res.json({ jobId, status: 'pending', credits_after: billingResult?.credits_after ?? null, cost: billingResult?.cost ?? 0 });
   } catch (err) {
     console.error('[Route] POST /generate', err);
     res.status(500).json({ error: err.message });
@@ -72,9 +87,17 @@ router.post('/post-image', async (req, res) => {
     const channel = await channelsSvc.getChannel(channelId, userId);
     if (!channel) return res.status(404).json({ error: 'Channel not found' });
 
+    // Списываем кредиты за картинку
+    let imgBilling = null;
+    if (userId) {
+      const ck = await billing.check(userId, 'image');
+      if (!ck.allowed) return res.status(402).json({ error: ck.reason, code: 'INSUFFICIENT_CREDITS', credits: ck.credits, cost: ck.cost });
+      imgBilling = await billing.spend(userId, 'image', { channel_id: channelId });
+    }
+
     const { generatePostImage } = require('../services/postImages');
     const result = await generatePostImage({ post, channel, style: channel.style || {} });
-    res.json(result);
+    res.json({ ...result, credits_after: imgBilling?.credits_after ?? null, cost: imgBilling?.cost ?? 0 });
   } catch (err) {
     console.error('[Route] POST /post-image', err);
     res.status(500).json({ error: err.message });