feat: Feature 3.4 — Stripe integration with founder code system

Subscription billing:
- POST /api/stripe/checkout — creates Stripe Checkout session
- POST /api/stripe/webhook — handles lifecycle events (raw body)
- POST /api/stripe/portal — customer self-service management
- GET /api/stripe/status — current subscription info

Founder code system:
- Validates codes against env var list with expiry date
- Routes to founder Stripe Price IDs (locked rate for life)
- 4 price objects: analyst, analyst-founder, desk, desk-founder

Webhook events handled:
- checkout.session.completed → tier update + founder status
- customer.subscription.deleted → revert to free tier
- invoice.payment_failed → logged

Lazy Stripe init (no API key required at import time).
Raw body middleware for webhook signature verification.

16 new tests, 237 total (210 Node.js + 27 Python), all passing.
Phase 3 Web MVP COMPLETE. All roadmap features shipped.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app.js

@@ -6,8 +6,13 @@ const scanRoutes = require('./routes/scan');
 const movementsRoutes = require('./routes/movements');
 const alertsRoutes = require('./routes/alerts');
 const betsRoutes = require('./routes/bets');
+const stripeRoutes = require('./routes/stripe');
 
 const app = express();
+
+// Stripe webhook needs raw body — must be before express.json()
+app.use('/api/stripe/webhook', express.raw({ type: 'application/json' }));
+
 app.use(express.json());
 app.use('/api/odds', oddsRoutes);
 app.use('/api/analyze', analyzeRoutes);
@@ -15,5 +20,6 @@ app.use('/api/scan', scanRoutes);
 app.use('/api/movements', movementsRoutes);
 app.use('/api/alerts', alertsRoutes);
 app.use('/api/bets', betsRoutes);
+app.use('/api/stripe', stripeRoutes);
 
 module.exports = app;