fix(client): address PR #141 review — parse-order, tween guard, test fixes

- Fix autoload parse-order violations: sim_bridge.gd, input_mapper.gd,
  audio_manager.gd now use load() for class_name types instead of
  direct references (LocalBridge, ServerProcess, Constants)
- Collapse redundant tween validity guard in dialogue_box.gd to
  is_instance_valid(panel) only
- Add clarifying comments to fog test resize assertions (8-tile
  padding trigger, 32x32 fixture assumption)
- Fix test_examine_display_sprint18 case 2: GameState.has() →
  "field" in GameState (Node vs Dictionary API)
- Fix test_game_state_sprint20: rename before_each → before_test
  (GdUnit4 lifecycle hook)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/ui/dialogue_box.gd

@@ -498,7 +498,7 @@ func _start_confrontation_beat(response_id: String, text: String) -> void:
 	if _active_tween and _active_tween.is_valid():
 		_active_tween.kill()
 	_active_tween = create_tween()
-	if _active_tween and _active_tween.is_valid() and is_instance_valid(panel):
+	if is_instance_valid(panel):
 		_active_tween.tween_property(panel, "modulate:a", CONFRONTATION_DIM_ALPHA, 0.2)
 
 	confrontation_monologue.emit(