perf(ai): optimize AI decision speed — fast clone, reduced search, time budget

SCOPONE-0005 iteration 8

- Replace JSON.parse/stringify deepClone with hand-written cloneState() (~10-50x faster)
- Export cloneState from engine.ts, use in applyMove and generateSamples
- Master: reduce samples 24→10 (14 endgame), depth 8→6 (8 endgame)
- Add 1.5s time budget with early termination in masterMove and alphaBeta
- evaluateFast(): single-pass pile scan, zero array allocations at leaf nodes
- Simplified move ordering in alphaBeta (captures-first, no per-move eval)
- Skip countScopaThreats when tableSum >= 11 (impossible to clear)
- Remove unused calcPrimiera import from ai.ts

src/game/engine.ts

@@ -126,7 +126,7 @@ export function applyMove(
   card: Card,
   captureChoice?: Card[]
 ): { nextState: GameState; capture: Capture | null; isScopa: boolean } {
-  const state2 = deepClone(state);
+  const state2 = cloneState(state);
   const player = state2.players[playerIdx];
 
   // Remove card from hand
@@ -294,6 +294,43 @@ export function getScoreBreakdown(state: GameState): ScoreBreakdown {
 // Helpers
 // ---------------------------------------------------------------------------
 
+function cloneCard(c: Card): Card {
+  return { suit: c.suit, value: c.value, id: c.id };
+}
+
+function clonePlayer(p: Player): Player {
+  return {
+    index: p.index,
+    hand: p.hand.map(cloneCard),
+    pile: p.pile.map(cloneCard),
+    scope: p.scope,
+    isHuman: p.isHuman,
+    name: p.name,
+  };
+}
+
+function cloneTeamScore(ts: TeamScore): TeamScore {
+  return { ...ts };
+}
+
+export function cloneState(state: GameState): GameState {
+  return {
+    players: [
+      clonePlayer(state.players[0]),
+      clonePlayer(state.players[1]),
+      clonePlayer(state.players[2]),
+      clonePlayer(state.players[3]),
+    ],
+    table: state.table.map(cloneCard),
+    currentPlayer: state.currentPlayer,
+    roundOver: state.roundOver,
+    gameOver: state.gameOver,
+    teamScores: [cloneTeamScore(state.teamScores[0]), cloneTeamScore(state.teamScores[1])],
+    lastCapturTeam: state.lastCapturTeam,
+    roundNumber: state.roundNumber,
+  };
+}
+
 function deepClone<T>(obj: T): T {
   return JSON.parse(JSON.stringify(obj));
 }