fix: resolve GDScript type errors and warnings

- Fix Array[Card] type mismatch in move_generator.gd (rank_counts arrays)
- Fix shadowed variables in card.gd (create, from_packed parameters)
- Fix integer division warning in deck.gd (/ → //)
- Fix unused_signal warnings in event_bus.gd (per-signal annotations)
- Fix unused_parameter warning in audio_manager.gd
- Normalize whitespace in training_controller.gd

project.godot

@@ -11,8 +11,10 @@ config_version=5
 [application]
 
 config/name="Guandan Card Game"
-config/version="0.1.0"
 config/description="掼蛋卡牌训练模式"
+config/version="0.1.0"
+run/main_scene="res://src/ui/scenes/main_menu.tscn"
+config/features=PackedStringArray("4.6")
 
 [autoload]