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>

supabase/migrations/002_line_movement.sql

@@ -0,0 +1,81 @@
+-- Feature 2.2 — Line Movement + Cascade Detection
+-- New tables: line_baselines, line_movements, cascade_alerts
+
+-- ============================================================
+-- TABLE: line_baselines
+-- Morning baseline lines for movement detection
+-- ============================================================
+CREATE TABLE public.line_baselines (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  sport TEXT NOT NULL,
+  game_date DATE NOT NULL,
+  player TEXT NOT NULL,
+  stat_type TEXT NOT NULL,
+  book TEXT NOT NULL,
+  baseline_line NUMERIC(5,1) NOT NULL,
+  captured_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE UNIQUE INDEX idx_baseline_unique ON public.line_baselines(game_date, player, stat_type, book);
+CREATE INDEX idx_baseline_date ON public.line_baselines(game_date);
+
+-- No RLS needed — server-only table, not user-facing
+
+-- ============================================================
+-- TABLE: line_movements
+-- Detected line movements throughout the day
+-- ============================================================
+CREATE TABLE public.line_movements (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  sport TEXT NOT NULL,
+  game_date DATE NOT NULL,
+  player TEXT NOT NULL,
+  stat_type TEXT NOT NULL,
+  book TEXT NOT NULL,
+  baseline_line NUMERIC(5,1) NOT NULL,
+  current_line NUMERIC(5,1) NOT NULL,
+  movement NUMERIC(4,1) NOT NULL,
+  direction TEXT NOT NULL CHECK (direction IN ('up', 'down')),
+  sharp_indicator TEXT CHECK (sharp_indicator IN ('sharp_action', 'public_action', 'unknown')),
+  detected_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_movements_date ON public.line_movements(game_date);
+CREATE INDEX idx_movements_player ON public.line_movements(player);
+
+-- No RLS needed — server-only table
+
+-- ============================================================
+-- TABLE: cascade_alerts
+-- Alerts for users whose scans are affected
+-- ============================================================
+CREATE TABLE public.cascade_alerts (
+  id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+  user_id UUID NOT NULL REFERENCES public.users(id) ON DELETE CASCADE,
+  alert_type TEXT NOT NULL CHECK (alert_type IN ('player_scratched', 'line_moved', 'parlay_regraded')),
+  scan_session_id UUID REFERENCES public.scan_sessions(id),
+  player TEXT,
+  detail TEXT NOT NULL,
+  is_read BOOLEAN NOT NULL DEFAULT false,
+  created_at TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_alerts_user ON public.cascade_alerts(user_id, is_read);
+
+ALTER TABLE public.cascade_alerts ENABLE ROW LEVEL SECURITY;
+
+CREATE POLICY "alerts_select_own" ON public.cascade_alerts
+  FOR SELECT USING (auth.uid() = user_id);
+
+CREATE POLICY "alerts_update_own" ON public.cascade_alerts
+  FOR UPDATE USING (auth.uid() = user_id)
+  WITH CHECK (auth.uid() = user_id);
+
+-- Cleanup: delete baselines older than 2 days (call periodically)
+CREATE OR REPLACE FUNCTION public.cleanup_old_baselines()
+RETURNS void AS $$
+BEGIN
+  DELETE FROM public.line_baselines WHERE game_date < (CURRENT_DATE - INTERVAL '2 days');
+  DELETE FROM public.line_movements WHERE game_date < (CURRENT_DATE - INTERVAL '2 days');
+END;
+$$ LANGUAGE plpgsql SECURITY DEFINER;