feat: Feature 1.5 — Bet Submission with 3 methods + performance tracking

Three submission methods:
- POST /api/bets/quickslip — structured bet entry
- POST /api/bets/screenshot — stub OCR with confirm flow
- POST /api/bets/sync — coming soon stub

Full bet lifecycle:
- PATCH /api/bets/:id/settle — settle with outcome, recalculates performance
- GET /api/bets — list with status/book/pagination filters
- GET /api/bets/performance — ROI, win rate, profit (weekly/monthly/all_time)

Payout calculator handles straight bets (American odds) and parlays
(multiplied leg payouts). Performance service recalculates on each
settlement and upserts into performance table.

33 new tests, 221 total (194 Node.js + 27 Python), all passing.
All backend features for Phase 1 + Phase 2 now complete.

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

tests/unit/payoutCalculator.test.js

@@ -0,0 +1,63 @@
+const { calculatePayout, calculateStraightPayout, calculateParlayPayout } = require('../../src/services/payoutCalculator');
+
+describe('payoutCalculator', () => {
+  describe('straight bets', () => {
+    test('negative odds: -110, $20 → $38.18', () => {
+      const payout = calculatePayout(20, 'straight', [-110]);
+      expect(payout).toBeCloseTo(38.18, 1);
+    });
+
+    test('positive odds: +150, $20 → $50', () => {
+      const payout = calculatePayout(20, 'straight', [150]);
+      expect(payout).toBe(50);
+    });
+
+    test('even odds: -100, $20 → $40', () => {
+      const payout = calculatePayout(20, 'straight', [-100]);
+      expect(payout).toBe(40);
+    });
+
+    test('heavy favorite: -200, $20 → $30', () => {
+      const payout = calculatePayout(20, 'straight', [-200]);
+      expect(payout).toBe(30);
+    });
+
+    test('big underdog: +300, $10 → $40', () => {
+      const payout = calculatePayout(10, 'straight', [300]);
+      expect(payout).toBe(40);
+    });
+  });
+
+  describe('parlay bets', () => {
+    test('2-leg parlay: -110 and -110, $20', () => {
+      const payout = calculatePayout(20, 'parlay', [-110, -110]);
+      // Each leg: 1 + 100/110 = 1.909..., product = 3.647, payout = 20 * 3.647 = 72.93
+      expect(payout).toBeCloseTo(72.93, 0);
+    });
+
+    test('3-leg parlay: -110, -110, +150, $10', () => {
+      const payout = calculatePayout(10, 'parlay', [-110, -110, 150]);
+      // 1.909 * 1.909 * 2.5 = 9.118, payout = 91.18
+      expect(payout).toBeCloseTo(91.18, 0);
+    });
+
+    test('2-leg parlay: +200 and +200, $10', () => {
+      const payout = calculatePayout(10, 'parlay', [200, 200]);
+      // 3 * 3 = 9, payout = 90
+      expect(payout).toBe(90);
+    });
+  });
+
+  describe('edge cases', () => {
+    test('empty odds returns amount', () => {
+      expect(calculatePayout(20, 'straight', [])).toBe(20);
+    });
+
+    test('single leg in parlay treated as straight', () => {
+      const straight = calculatePayout(20, 'straight', [-110]);
+      const parlaySingle = calculatePayout(20, 'parlay', [-110]);
+      // Single leg parlay should use parlay calc but result is same as straight
+      expect(parlaySingle).toBeCloseTo(straight, 1);
+    });
+  });
+});