feat: Feature 2.1 — Parlay Scan with correlation detection + monetization

POST /api/scan/parlay — authenticated parlay analysis:
- Supabase JWT auth middleware (auth.getUser verification)
- 5 correlation types detected between legs (same_game, same_team,
  same_player_conflicting, positive_correlation, blowout_cascade)
- Overall parlay grading (A/B/C/D) with correlation penalty adjustments
- Free tier: 5 scans/month, atomic scan count increment
- Scan 5: full analysis + personalized upgrade pitch
- Scan 6+: 403 block with upgrade pitch
- Pitch personalization from scan history (top stats, grades, tier rec)
- DB writes: picks + scan_sessions per scan

30 new tests, 158 total (131 Node.js + 27 Python), all passing

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

src/app.js

@@ -2,10 +2,12 @@ require('dotenv').config();
 const express = require('express');
 const oddsRoutes = require('./routes/odds');
 const analyzeRoutes = require('./routes/analyze');
+const scanRoutes = require('./routes/scan');
 
 const app = express();
 app.use(express.json());
 app.use('/api/odds', oddsRoutes);
 app.use('/api/analyze', analyzeRoutes);
+app.use('/api/scan', scanRoutes);
 
 module.exports = app;