feat(core): implement room navigation, character states, save/load and settings menu

- RoomNavigator autoload: smooth camera pan between floors
- Floor1 and Floor2 placeholder rooms with elevator buttons
- CharacterData Resource with State enum (HEALTHY/SICK/SLEEPING/TIRED)
- Character visual state feedback via ColorRect color
- Main scene loads saved state on startup
- SettingsMenu with music/sfx sliders and game reset
- HUD settings button to open SettingsMenu

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

scripts/systems/hud.gd

@@ -1,10 +1,11 @@
-## HUD — heads-up display with back button and music toggle.
+## HUD — heads-up display with back button, music toggle, and settings access.
 extends CanvasLayer
 
 const MUSIC_ON_SYMBOL: String = "♪"
 const MUSIC_OFF_SYMBOL: String = "✕"
 
 var _music_enabled: bool = true
+@onready var _settings_menu: SettingsMenu = get_node_or_null("/root/Main/UI/SettingsMenu") as SettingsMenu
 
 
 func _on_back_button_pressed() -> void:
@@ -18,3 +19,8 @@ func _on_music_toggle_pressed() -> void:
 	var btn: Button = get_node_or_null("MusicToggle") as Button
 	if btn != null:
 		btn.text = MUSIC_ON_SYMBOL if _music_enabled else MUSIC_OFF_SYMBOL
+
+
+func _on_settings_button_pressed() -> void:
+	if _settings_menu != null:
+		_settings_menu.show_menu()

scripts/systems/room_navigator.gd

@@ -0,0 +1,30 @@
+## RoomNavigator — autoload that moves the Camera2D smoothly between hospital floors.
+extends Node
+
+signal room_changed(floor_index: int)
+
+const FLOOR_HEIGHT: float = 720.0
+const CAMERA_TWEEN_DURATION: float = 0.6
+
+var _current_floor: int = 0
+var _camera: Camera2D
+
+
+func initialize(camera: Camera2D) -> void:
+	_camera = camera
+
+
+func go_to_floor(floor_index: int) -> void:
+	if _camera == null or floor_index == _current_floor:
+		return
+	_current_floor = floor_index
+	var target_y: float = floor_index * -FLOOR_HEIGHT
+	var tween: Tween = _camera.create_tween()
+	tween.set_ease(Tween.EASE_IN_OUT)
+	tween.set_trans(Tween.TRANS_SINE)
+	tween.tween_property(_camera, "position:y", target_y, CAMERA_TWEEN_DURATION)
+	room_changed.emit(floor_index)
+
+
+func get_current_floor() -> int:
+	return _current_floor

scripts/systems/settings_menu.gd

@@ -0,0 +1,37 @@
+## SettingsMenu — overlay panel for audio volume and game reset.
+class_name SettingsMenu extends CanvasLayer
+
+
+func _ready() -> void:
+	visible = false
+
+
+func show_menu() -> void:
+	visible = true
+
+
+func hide_menu() -> void:
+	visible = false
+
+
+func _on_music_slider_value_changed(value: float) -> void:
+	AudioManager.set_music_volume(value)
+
+
+func _on_sfx_slider_value_changed(value: float) -> void:
+	AudioManager.set_sfx_volume(value)
+
+
+func _on_reset_button_pressed() -> void:
+	var dialog: ConfirmationDialog = get_node_or_null("Panel/ResetConfirmDialog") as ConfirmationDialog
+	if dialog != null:
+		dialog.popup_centered()
+
+
+func _on_reset_confirmed() -> void:
+	SaveManager.reset_game()
+	get_tree().reload_current_scene()
+
+
+func _on_close_button_pressed() -> void:
+	hide_menu()