feat: Feature 2.2 — Line Movement + Cascade Detection

Line movement system:
- Baseline capture on first odds fetch of the day
- Movement detection >= 0.5 points with direction (up/down)
- Sharp money heuristic (sharp_action/public_action/unknown)
- GET /api/movements with player, stat_type, min_movement filters
- Movements included in GET /api/odds/nba live responses

Cascade detection system:
- Scratch detection: player props disappear from 2+ books
- Affected user lookup via scan_sessions + picks
- Parlay re-grade without scratched legs
- cascade_alerts created for affected users
- GET /api/alerts (Analyst/Desk only), PATCH /api/alerts/:id/read

Zero extra Odds API credits — all detection piggybacks on existing fetches.
Migration 002: line_baselines, line_movements, cascade_alerts tables.

30 new tests, 188 total (161 Node.js + 27 Python), all passing.
Phase 2 Core Product COMPLETE.

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

src/routes/odds.js

@@ -89,13 +89,19 @@ router.get('/nba', async (req, res) => {
       res.set('X-BetonBLK-Stale', 'true');
     }
 
-    return res.json({
+    const response = {
       sport: 'nba',
       updated_at: result.updated_at,
       source: result.source,
       quota_remaining: result.quota_remaining,
       props,
-    });
+    };
+
+    if (result.movements && result.movements.length > 0) {
+      response.movements = result.movements;
+    }
+
+    return res.json(response);
   } catch (err) {
     const status = err.statusCode || 500;
     return res.status(status).json({ error: err.message });