feat(poc): implement Sprint 1 proof of concept

- project.godot with autoload configuration
- Reception room with placeholder visuals
- Draggable Character with DragDropComponent
- Interactive flower object with bounce animation
- GameState, SaveManager, AudioManager, InputManager autoloads
- HUD with back button and music toggle

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

scripts/autoload/AudioManager.gd

@@ -0,0 +1,63 @@
+## AudioManager — music playback with cross-fade, SFX playback, volume control.
+extends Node
+
+const DEFAULT_MUSIC_VOLUME: float = 0.6
+const CROSSFADE_DURATION: float = 1.0
+
+var _music_player_a: AudioStreamPlayer
+var _music_player_b: AudioStreamPlayer
+var _active_player: AudioStreamPlayer
+var _sfx_player: AudioStreamPlayer
+var _music_volume: float = DEFAULT_MUSIC_VOLUME
+var _sfx_volume: float = 1.0
+var _is_fading: bool = false
+
+
+func _ready() -> void:
+	_music_player_a = AudioStreamPlayer.new()
+	_music_player_b = AudioStreamPlayer.new()
+	_sfx_player = AudioStreamPlayer.new()
+	add_child(_music_player_a)
+	add_child(_music_player_b)
+	add_child(_sfx_player)
+	_active_player = _music_player_a
+	_apply_music_volume()
+
+
+func play_music(stream: AudioStream) -> void:
+	if _active_player.stream == stream and _active_player.playing:
+		return
+	var next_player: AudioStreamPlayer = _music_player_b if _active_player == _music_player_a else _music_player_a
+	next_player.stream = stream
+	next_player.volume_db = linear_to_db(0.0)
+	next_player.play()
+	var tween: Tween = create_tween()
+	tween.set_parallel(true)
+	tween.tween_property(_active_player, "volume_db", linear_to_db(0.0), CROSSFADE_DURATION)
+	tween.tween_property(next_player, "volume_db", linear_to_db(_music_volume), CROSSFADE_DURATION)
+	var prev_player: AudioStreamPlayer = _active_player
+	tween.tween_callback(prev_player.stop).set_delay(CROSSFADE_DURATION)
+	_active_player = next_player
+
+
+func play_sfx(stream: AudioStream) -> void:
+	_sfx_player.stream = stream
+	_sfx_player.volume_db = linear_to_db(_sfx_volume)
+	_sfx_player.play()
+
+
+func set_music_volume(value: float) -> void:
+	_music_volume = clampf(value, 0.0, 1.0)
+	_apply_music_volume()
+
+
+func set_sfx_volume(value: float) -> void:
+	_sfx_volume = clampf(value, 0.0, 1.0)
+
+
+func get_music_volume() -> float:
+	return _music_volume
+
+
+func _apply_music_volume() -> void:
+	_active_player.volume_db = linear_to_db(_music_volume)

scripts/autoload/GameState.gd

@@ -0,0 +1,45 @@
+## GameState — global game state: character positions, object states, current room.
+extends Node
+
+signal state_changed
+signal character_moved(character_id: String, position: Vector2)
+
+var _character_positions: Dictionary = {}
+var _object_states: Dictionary = {}
+var current_room: String = "reception"
+
+
+func get_character_position(id: String) -> Vector2:
+	return _character_positions.get(id, Vector2.ZERO)
+
+
+func set_character_position(id: String, pos: Vector2) -> void:
+	_character_positions[id] = pos
+	character_moved.emit(id, pos)
+	state_changed.emit()
+
+
+func get_object_state(id: String) -> String:
+	return _object_states.get(id, "idle")
+
+
+func set_object_state(id: String, state: String) -> void:
+	_object_states[id] = state
+	state_changed.emit()
+
+
+func get_save_data() -> Dictionary:
+	return {
+		"character_positions": _character_positions,
+		"object_states": _object_states,
+		"current_room": current_room,
+	}
+
+
+func apply_save_data(data: Dictionary) -> void:
+	if data.has("character_positions"):
+		_character_positions = data["character_positions"]
+	if data.has("object_states"):
+		_object_states = data["object_states"]
+	if data.has("current_room"):
+		current_room = data["current_room"]

scripts/autoload/InputManager.gd

@@ -0,0 +1,30 @@
+## InputManager — abstracts touch and mouse input into unified drag signals.
+extends Node
+
+signal drag_started(position: Vector2)
+signal drag_moved(position: Vector2)
+signal drag_ended(position: Vector2)
+
+var _is_dragging: bool = false
+
+
+func _input(event: InputEvent) -> void:
+	if event is InputEventScreenTouch:
+		if event.pressed:
+			_is_dragging = true
+			drag_started.emit(event.position)
+		else:
+			_is_dragging = false
+			drag_ended.emit(event.position)
+	elif event is InputEventScreenDrag:
+		if _is_dragging:
+			drag_moved.emit(event.position)
+	elif event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT:
+		if event.pressed:
+			_is_dragging = true
+			drag_started.emit(event.position)
+		else:
+			_is_dragging = false
+			drag_ended.emit(event.position)
+	elif event is InputEventMouseMotion and _is_dragging:
+		drag_moved.emit(event.position)

scripts/autoload/SaveManager.gd

@@ -0,0 +1,40 @@
+## SaveManager — persists game state as JSON to user://savegame.json, auto-saves on state_changed.
+extends Node
+
+const SAVE_PATH: String = "user://savegame.json"
+
+
+func _ready() -> void:
+	GameState.state_changed.connect(_on_state_changed)
+
+
+func save_game() -> void:
+	var data: Dictionary = GameState.get_save_data()
+	var file: FileAccess = FileAccess.open(SAVE_PATH, FileAccess.WRITE)
+	if file == null:
+		return
+	file.store_string(JSON.stringify(data))
+	file.close()
+
+
+func load_game() -> void:
+	if not FileAccess.file_exists(SAVE_PATH):
+		return
+	var file: FileAccess = FileAccess.open(SAVE_PATH, FileAccess.READ)
+	if file == null:
+		return
+	var raw: String = file.get_as_text()
+	file.close()
+	var parsed = JSON.parse_string(raw)
+	if parsed is Dictionary:
+		GameState.apply_save_data(parsed)
+
+
+func reset_game() -> void:
+	if FileAccess.file_exists(SAVE_PATH):
+		DirAccess.remove_absolute(SAVE_PATH)
+	GameState.apply_save_data({})
+
+
+func _on_state_changed() -> void:
+	save_game()