feat(sprint-22): character SFX + UltrasoundMachine ambient heartbeat

docs/audio-assets-sprint19.md

@@ -79,3 +79,17 @@ All CC0 or CC-BY from freesound.org. Replace placeholder 0-byte files with the d
 | `assets/audio/sfx/object_tap.ogg` | soft tap / click | search "soft tap" or "gentle click" |
 
 All files must be <1.5 s, child-friendly (no harsh/loud sounds), mono or stereo, 44100 Hz, OGG Vorbis.
+
+## Sprint 22 — Character & Ambient SFX
+
+All CC0 or CC-BY from freesound.org. Replace placeholder 0-byte files with the downloads below.
+
+| File | Description | Freesound suggestion |
+|---|---|---|
+| `assets/audio/sfx/ultrasound_heartbeat.ogg` | soft beep/blip ~1s, loops seamlessly | search "heartbeat beep soft" or "medical monitor beep" |
+| `assets/audio/sfx/character_pickup.ogg` | happy soft squeak / whoosh | search "cartoon pickup soft" or "whoosh gentle" |
+| `assets/audio/sfx/character_place.ogg` | gentle thud / landing | search "soft thud" or "gentle landing" |
+| `assets/audio/sfx/character_tap.ogg` | short happy chime / pop | search "happy chime short" or "cartoon pop soft" |
+
+All files must be child-friendly (no harsh/loud sounds), mono or stereo, 44100 Hz, OGG Vorbis.
+`ultrasound_heartbeat.ogg` must loop seamlessly (start and end points match).

scripts/autoload/AudioManager.gd

@@ -27,6 +27,9 @@ const _SFX_MAP: Dictionary = {
 	"ambulance_siren":   "res://assets/audio/sfx/ambulance_siren.ogg",
 	"delivery_cheer":    "res://assets/audio/sfx/delivery_cheer.ogg",
 	"object_tap":        "res://assets/audio/sfx/object_tap.ogg",
+	"character_pickup":  "res://assets/audio/sfx/character_pickup.ogg",
+	"character_place":   "res://assets/audio/sfx/character_place.ogg",
+	"character_tap":     "res://assets/audio/sfx/character_tap.ogg",
 }
 
 var _current_floor: int = -1

scripts/characters/character.gd

@@ -187,6 +187,7 @@ func _handle_outfit_tap() -> void:
 
 
 func _on_drag_picked_up(pos: Vector2) -> void:
+	AudioManager.play_sfx("character_pickup")
 	_is_held = true
 	_drag_start_position = pos
 	set_animation_state("held")
@@ -197,9 +198,11 @@ func _on_drag_released(pos: Vector2) -> void:
 	_is_held = false
 	var drag_distance: float = pos.distance_to(_drag_start_position)
 	if drag_distance < _TAP_THRESHOLD:
+		AudioManager.play_sfx("character_tap")
 		set_animation_state("idle")
 		_handle_outfit_tap()
 		return
+	AudioManager.play_sfx("character_place")
 	set_animation_state("idle")
 	if data == null or data.id.is_empty():
 		return

scripts/objects/ultrasound_machine.gd

@@ -1,4 +1,5 @@
 ## UltrasoundMachine — displays a continuous heartbeat pulse on the screen.
+## Plays looping ambient heartbeat audio when the ultrasound room is active.
 class_name UltrasoundMachine extends Node2D
 
 const BEAT_RISE_DURATION: float = 0.12
@@ -6,10 +7,50 @@ const BEAT_FALL_DURATION: float = 0.12
 const BEAT_INTERVAL: float = 0.60
 const BEAT_SCALE_PEAK: Vector2 = Vector2(1.5, 1.5)
 const BEAT_SCALE_REST: Vector2 = Vector2(1.0, 1.0)
+const _HEARTBEAT_PATH: String = "res://assets/audio/sfx/ultrasound_heartbeat.ogg"
+
+@export var trigger_floor: int = 2
+@export var trigger_room: int = 0
+
+var _audio: AudioStreamPlayer
 
 
 func _ready() -> void:
 	_start_heartbeat_loop()
+	_setup_audio()
+	RoomNavigator.room_changed.connect(_on_room_changed)
+
+
+func _exit_tree() -> void:
+	if RoomNavigator.room_changed.is_connected(_on_room_changed):
+		RoomNavigator.room_changed.disconnect(_on_room_changed)
+
+
+func _setup_audio() -> void:
+	_audio = AudioStreamPlayer.new()
+	add_child(_audio)
+	if AudioServer.get_driver_name() == "Dummy":
+		return
+	if not ResourceLoader.exists(_HEARTBEAT_PATH):
+		return
+	var base: AudioStream = load(_HEARTBEAT_PATH) as AudioStream
+	if base == null:
+		return
+	var ogg: AudioStreamOggVorbis = base as AudioStreamOggVorbis
+	if ogg == null:
+		return
+	ogg = ogg.duplicate() as AudioStreamOggVorbis
+	ogg.loop = true
+	_audio.stream = ogg
+
+
+func _on_room_changed(floor_index: int, room_index: int) -> void:
+	if _audio == null or _audio.stream == null:
+		return
+	if floor_index == trigger_floor and room_index == trigger_room:
+		_audio.play()
+	else:
+		_audio.stop()
 
 
 func _start_heartbeat_loop() -> void:

test/unit/test_audio_manager.gd

@@ -83,3 +83,9 @@ func test_sfx_map_has_all_interactive_object_keys() -> void:
 	assert_true(AudioManager._SFX_MAP.has("ambulance_siren"))
 	assert_true(AudioManager._SFX_MAP.has("delivery_cheer"))
 	assert_true(AudioManager._SFX_MAP.has("object_tap"))
+
+
+func test_sfx_map_has_all_character_keys() -> void:
+	assert_true(AudioManager._SFX_MAP.has("character_pickup"))
+	assert_true(AudioManager._SFX_MAP.has("character_place"))
+	assert_true(AudioManager._SFX_MAP.has("character_tap"))