fix(client): address PR #67 round 2 — broken tests, BBCode escape, expiry loop

- Add missing _test_input_queue proxy to SimBridge (26 call sites across
  6 test files broken by TestHarness extraction)
- Parent quit dialog to SceneTree root instead of caller node to prevent
  orphaned reference if caller freed before user responds
- Remove deprecated rng.randomize() call (Godot 4 auto-seeds)
- Clear debug overlay state (_npc_paths, tick timing) on session change
  via new GameState.game_id_changed signal to prevent entity ID collisions
- Update settings_dialog quit_to_menu() call site (no-arg signature)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/scripts/autoloads/sim_bridge.gd

@@ -72,6 +72,9 @@ var _test_npc_relationship: String:
 	set(v):
 		if harness: harness.npc_relationship = v
 
+var _test_input_queue: Array:
+	get: return harness.input_queue if harness else []
+
 
 # -- Connection lifecycle ------------------------------------------------------