feat: betting system — Cashu escrow, Lightning deposit/withdraw, payouts

Complete betting infrastructure:
- Bets schema (SQLite) with escrow status tracking
- Cashu token verification + minting (stub for real mint)
- Lightning invoice creation + withdrawal (stub for real LN node)
- Bet placement with odds lock, settlement on fight end
- Payout automation for winners, refunds on draws
- Bet history by pubkey + fight pool info
- Verifiable bet proofs for transparency
- API routes: /api/bets/{odds,place,fight,history,deposit,withdraw}

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/db/schema.ts

@@ -55,3 +55,20 @@ export const rounds = sqliteTable('rounds', {
   narration: text('narration'),
   createdAt: text('created_at').notNull(),
 })
+
+export const bets = sqliteTable('bets', {
+  id: text('id').primaryKey(),
+  fightId: text('fight_id').notNull().references(() => fights.id),
+  bettorPubkey: text('bettor_pubkey').notNull(),
+  botId: text('bot_id').notNull().references(() => bots.id),
+  amountSats: integer('amount_sats').notNull(),
+  oddsAtPlacement: real('odds_at_placement').notNull(),
+  cashuToken: text('cashu_token').notNull(),
+  status: text('status', {
+    enum: ['pending', 'locked', 'won', 'lost', 'refunded', 'paid'],
+  }).notNull().default('pending'),
+  payoutSats: integer('payout_sats'),
+  payoutToken: text('payout_token'),
+  createdAt: text('created_at').notNull(),
+  settledAt: text('settled_at'),
+})