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>

tests/unit/migration002.test.js

@@ -0,0 +1,46 @@
+const fs = require('fs');
+const path = require('path');
+
+const sql = fs.readFileSync(
+  path.join(__dirname, '../../supabase/migrations/002_line_movement.sql'),
+  'utf8'
+);
+
+describe('Migration 002 — Line Movement', () => {
+  test('creates line_baselines table', () => {
+    expect(sql).toContain('CREATE TABLE public.line_baselines');
+  });
+
+  test('creates line_movements table', () => {
+    expect(sql).toContain('CREATE TABLE public.line_movements');
+  });
+
+  test('creates cascade_alerts table', () => {
+    expect(sql).toContain('CREATE TABLE public.cascade_alerts');
+  });
+
+  test('line_movements has direction constraint', () => {
+    expect(sql).toMatch(/direction.*CHECK.*\(direction IN \('up',\s*'down'\)\)/);
+  });
+
+  test('cascade_alerts has alert_type constraint', () => {
+    expect(sql).toMatch(/alert_type.*CHECK.*\(alert_type IN/);
+  });
+
+  test('cascade_alerts has RLS enabled', () => {
+    expect(sql).toContain('ALTER TABLE public.cascade_alerts ENABLE ROW LEVEL SECURITY');
+  });
+
+  test('cascade_alerts has select and update policies', () => {
+    expect(sql).toContain('CREATE POLICY "alerts_select_own"');
+    expect(sql).toContain('CREATE POLICY "alerts_update_own"');
+  });
+
+  test('unique index on baselines prevents duplicates', () => {
+    expect(sql).toContain('CREATE UNIQUE INDEX idx_baseline_unique');
+  });
+
+  test('cleanup function exists', () => {
+    expect(sql).toContain('CREATE OR REPLACE FUNCTION public.cleanup_old_baselines');
+  });
+});