feat: add L1 Basic AI and L2 Rule AI with heuristic scoring

src/ai/l1_basic_ai.gd

@@ -0,0 +1,53 @@
+# src/ai/l1_basic_ai.gd
+class_name L1BasicAI
+extends BaseAI
+
+const _C = preload("res://src/core/constants.gd")
+
+func _init():
+    ai_name = "Basic AI"
+
+func decide(hand: Array, table: Array, current_rank: int, config: RuleConfig) -> HandEvaluator.EvaluatedPlay:
+    var moves := MoveGenerator.generate(hand, current_rank, config)
+    var last_play := _last_non_pass(table)
+    if last_play == null:
+        return _smallest_play(moves)
+    var candidates: Array = []
+    for m in moves:
+        if m.type == -1:
+            continue
+        if m.type == last_play.type and m.primary_rank > last_play.primary_rank:
+            candidates.append(m)
+        elif (m.type == _C.TYPE_BOMB or m.type == _C.TYPE_ROCKET) and _beats(m, last_play, config):
+            candidates.append(m)
+    if candidates.is_empty():
+        return _pass_move()
+    return _smallest_play(candidates)
+
+func _smallest_play(moves: Array) -> HandEvaluator.EvaluatedPlay:
+    var best: HandEvaluator.EvaluatedPlay = null
+    for m in moves:
+        if m.type <= 0:
+            continue
+        if best == null or m.cards.size() < best.cards.size():
+            best = m
+        elif m.cards.size() == best.cards.size() and m.primary_rank < best.primary_rank:
+            best = m
+    if best == null:
+        return _pass_move()
+    return best
+
+func _last_non_pass(table: Array) -> HandEvaluator.EvaluatedPlay:
+    for i in range(table.size() - 1, -1, -1):
+        if table[i].type != -1:
+            return table[i]
+    return null
+
+func _beats(a: HandEvaluator.EvaluatedPlay, b: HandEvaluator.EvaluatedPlay, config: RuleConfig) -> bool:
+    return RuleEngine.compare(a, b, config) > 0
+
+func _pass_move() -> HandEvaluator.EvaluatedPlay:
+    var p := HandEvaluator.EvaluatedPlay.new()
+    p.type = -1
+    p.primary_rank = 0
+    return p