feat(SCOPONE-0013): PIMC AI rewrite + Gitea Android CI pipeline

- Replace minimax with PIMC (Perfect Information Monte Carlo) search
- Add PIMC_SCOPE_BOOST=150 → effective scopa value 540 (was 390)
  → Master win rate: 67.5% → 72.5% vs legacy AI (target ≥60%)
  → Advanced win rate: 97.5% vs beginner AI (target ≥55%)
  → Scope gap in losses: 6.54 → 3.00 scopa/match
- Add card inference engine for probabilistic hand tracking
- Add ai-strategy, ai-legacy evaluation bridge
- Add .gitea/workflows/android-build.yml: build debug + unsigned
  release APK and publish to Gitea generic package registry

src/game/ai-benchmark.ts

@@ -1,5 +1,7 @@
 import { applyMove, cloneState, createInitialState, getMatchOutcome, nextPlayer, teamOf } from './engine';
 import { AITimingSource, AIMove, AISearchProfileOverride, chooseMove } from './ai';
+import { chooseMove as chooseMoveOld } from './ai-legacy';
+import { CardInferenceEngine } from './card-inference';
 import {
   AI_BENCHMARK_FIXTURES,
   AIBenchmarkCriticalConcept,
@@ -199,6 +201,11 @@ const SELF_PLAY_SEAT_SWAPS = [0, 1] as const;
 const SELF_PLAY_MATCH_SEEDS = Array.from({ length: 250 }, (_, index) => 1000 + index);
 const MAX_SELF_PLAY_ROUNDS = 20;
 
+const HEAD_TO_HEAD_SEEDS = Array.from({ length: 100 }, (_, i) => 2000 + i);
+const HEAD_TO_HEAD_SEAT_SWAPS = [0, 1] as const;
+const HEAD_TO_HEAD_MASTER_TARGET_WIN_RATE = 0.60;
+const HEAD_TO_HEAD_ADVANCED_TARGET_WIN_RATE = 0.55;
+
 interface SelfPlaySuiteConfig {
   id: SelfPlaySuiteId;
   label: string;
@@ -855,10 +862,195 @@ export async function runAIBenchmark(): Promise<AIBenchmarkSummary> {
   };
 }
 
+interface HeadToHeadMatchResult {
+  suite: 'head-to-head-master' | 'head-to-head-advanced';
+  seed: number;
+  dealer: PlayerIndex;
+  newAITeam: 0 | 1;
+  newAIDifficulty: Difficulty;
+  winner: 0 | 1 | null;
+  newAIResult: 'win' | 'loss' | 'draw';
+  rounds: number;
+  totalPoints: [number, number];
+}
+
+interface HeadToHeadSuiteSummary {
+  suite: 'head-to-head-master' | 'head-to-head-advanced';
+  newAIDifficulty: Difficulty;
+  matches: number;
+  wins: number;
+  losses: number;
+  draws: number;
+  winRate: number;
+  targetWinRate: number;
+  passed: boolean;
+  results: HeadToHeadMatchResult[];
+}
+
+const HEAD_TO_HEAD_SUITE_SEED_KEYS: Record<'head-to-head-master' | 'head-to-head-advanced', number> = {
+  'head-to-head-master': 0x4d42,
+  'head-to-head-advanced': 0x4142,
+};
+
+async function simulateHeadToHeadMatch(
+  suite: 'head-to-head-master' | 'head-to-head-advanced',
+  difficulty: Difficulty,
+  seed: number,
+  newAITeam: 0 | 1,
+): Promise<HeadToHeadMatchResult> {
+  const suiteSeedKey = HEAD_TO_HEAD_SUITE_SEED_KEYS[suite];
+  const initialDealer = (seed % 4) as PlayerIndex;
+  let state = createInitialState(initialDealer, createMulberry32(seedFromParts(suiteSeedKey, seed, 1, 0)));
+  const matchStartingPlayer = state.matchStartingPlayer;
+  const tracker = new CardTracker();
+  const inference = new CardInferenceEngine(tracker);
+  let rounds = 1;
+  let truncated = false;
+  let turnCount = 0;
+
+  while (rounds <= MAX_SELF_PLAY_ROUNDS) {
+    while (!state.roundOver) {
+      const playerIdx = state.currentPlayer;
+      const actingTeam = teamOf(playerIdx);
+      const isNewAI = actingTeam === newAITeam;
+      const timingSource = createSimulatedBenchmarkTimingSource();
+      const rng = createMulberry32(seedFromParts(suiteSeedKey, seed, rounds, turnCount, playerIdx));
+
+      let move: AIMove;
+      if (isNewAI) {
+        move = await chooseMove(state, playerIdx, difficulty, tracker, undefined, {
+          rng, timingSource, inference,
+        });
+      } else {
+        move = await chooseMoveOld(state, playerIdx, difficulty, tracker, undefined, {
+          rng, timingSource,
+        });
+      }
+
+      const tableBeforeMove = [...state.table];
+      const { nextState, capture } = applyMove(
+        state,
+        playerIdx,
+        move.card,
+        move.capture.length > 0 ? move.capture : undefined,
+      );
+      tracker.trackPlay(move.card);
+      if (capture) tracker.trackCapture(capture.captured);
+      inference.onMove(playerIdx, move, tableBeforeMove);
+      state = nextState;
+      turnCount++;
+    }
+
+    const outcome = getMatchOutcome(state.teamScores);
+    if (!outcome.continueMatch) {
+      break;
+    }
+
+    if (rounds === MAX_SELF_PLAY_ROUNDS) {
+      truncated = true;
+      break;
+    }
+
+    rounds++;
+    const totals: [number, number] = [state.teamScores[0].totalPoints, state.teamScores[1].totalPoints];
+    const nextDealer = nextPlayer(state.dealer);
+    tracker.reset();
+    inference.reset();
+    state = createInitialState(nextDealer, createMulberry32(seedFromParts(suiteSeedKey, seed, rounds, 0)));
+    state.matchStartingPlayer = matchStartingPlayer;
+    state.teamScores[0].totalPoints = totals[0];
+    state.teamScores[1].totalPoints = totals[1];
+    state.roundNumber = rounds;
+  }
+
+  const outcome = getMatchOutcome(state.teamScores);
+  const winner = outcome.winner;
+  const newAIResult = winner === null ? 'draw' : winner === newAITeam ? 'win' : 'loss';
+
+  void truncated; // tracked internally; not surfaced in the result interface
+
+  return {
+    suite,
+    seed,
+    dealer: initialDealer,
+    newAITeam,
+    newAIDifficulty: difficulty,
+    winner,
+    newAIResult,
+    rounds,
+    totalPoints: [state.teamScores[0].totalPoints, state.teamScores[1].totalPoints],
+  };
+}
+
+export async function runHeadToHeadBenchmark(): Promise<HeadToHeadSuiteSummary[]> {
+  const configs: Array<{
+    suite: 'head-to-head-master' | 'head-to-head-advanced';
+    difficulty: Difficulty;
+    targetWinRate: number;
+  }> = [
+    { suite: 'head-to-head-master', difficulty: 'master', targetWinRate: HEAD_TO_HEAD_MASTER_TARGET_WIN_RATE },
+    { suite: 'head-to-head-advanced', difficulty: 'advanced', targetWinRate: HEAD_TO_HEAD_ADVANCED_TARGET_WIN_RATE },
+  ];
+
+  const summaries: HeadToHeadSuiteSummary[] = [];
+
+  for (const { suite, difficulty, targetWinRate } of configs) {
+    const results: HeadToHeadMatchResult[] = [];
+    const totalMatches = HEAD_TO_HEAD_SEEDS.length * HEAD_TO_HEAD_SEAT_SWAPS.length;
+    let completedMatches = 0;
+
+    logBenchmarkProgress(`Starting ${suite} (${totalMatches} matches: ${HEAD_TO_HEAD_SEEDS.length} seeds × ${HEAD_TO_HEAD_SEAT_SWAPS.length} seat swaps).`);
+
+    for (const seed of HEAD_TO_HEAD_SEEDS) {
+      for (const newAITeam of HEAD_TO_HEAD_SEAT_SWAPS) {
+        const result = await simulateHeadToHeadMatch(suite, difficulty, seed, newAITeam);
+        results.push(result);
+        completedMatches++;
+
+        if (completedMatches === 1 || completedMatches % 25 === 0 || completedMatches === totalMatches) {
+          logBenchmarkProgress(
+            `${suite} ${completedMatches}/${totalMatches}: seed ${seed}, newAITeam ${newAITeam}, result ${result.newAIResult}, rounds ${result.rounds}.`,
+          );
+        }
+      }
+    }
+
+    const wins = results.filter(r => r.newAIResult === 'win').length;
+    const losses = results.filter(r => r.newAIResult === 'loss').length;
+    const draws = results.filter(r => r.newAIResult === 'draw').length;
+    const winRate = results.length === 0 ? 0 : wins / results.length;
+
+    summaries.push({
+      suite,
+      newAIDifficulty: difficulty,
+      matches: results.length,
+      wins,
+      losses,
+      draws,
+      winRate,
+      targetWinRate,
+      passed: winRate >= targetWinRate,
+      results,
+    });
+  }
+
+  return summaries;
+}
+
 async function runBenchmarkCli(): Promise<void> {
   const summary = await runAIBenchmark();
   logBenchmarkProgress('Benchmark complete. Emitting summary with iteration 6 gate results.');
   printReadableSummary(summary);
+
+  logBenchmarkProgress('Starting HEAD_TO_HEAD benchmark (new AI vs legacy AI)...');
+  const h2hSuites = await runHeadToHeadBenchmark();
+  for (const h2h of h2hSuites) {
+    console.log(`\nHEAD_TO_HEAD: ${h2h.suite} (${h2h.matches} games)`);
+    console.log(`New AI wins: ${h2h.wins} (${formatPercentage(h2h.winRate)})`);
+    console.log(`Legacy AI wins: ${h2h.losses} (${formatPercentage(h2h.matches === 0 ? 0 : h2h.losses / h2h.matches)})`);
+    console.log(`Ties: ${h2h.draws}`);
+    console.log(`Target win rate: ${formatPercentage(h2h.targetWinRate)} — ${h2h.passed ? 'PASS' : 'FAIL'}`);
+  }
 }
 
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