feat(audio): add wall contact cue

Game/scripts/audio_manager.gd

@@ -9,6 +9,7 @@ const MAX_INTENSITY := 1.0
 var enabled := true
 var _engine_player: AudioStreamPlayer
 var _engine_turbo := false
+var _last_wall_scrape_ms := -1000
 
 
 func bind_tree_buttons(root: Node) -> void:
@@ -44,6 +45,17 @@ func play_impact(intensity: float) -> void:
 	_play_tone(150.0 + 180.0 * amount, 0.06 + 0.08 * amount, 0.08 + 0.18 * amount)
 
 
+func play_wall_scrape(intensity: float) -> void:
+	var amount := clamp_intensity(intensity)
+	if amount <= 0.0:
+		return
+	var now_ms := Time.get_ticks_msec()
+	if now_ms - _last_wall_scrape_ms < 80:
+		return
+	_last_wall_scrape_ms = now_ms
+	_play_tone(110.0 + 90.0 * amount, 0.05 + 0.07 * amount, 0.05 + 0.10 * amount)
+
+
 func play_goal() -> void:
 	_play_tone(523.25, 0.22, 0.22)
 	_play_tone(783.99, 0.30, 0.18)

Game/scripts/ship.gd

@@ -197,6 +197,7 @@ signal thrust_changed(thrust_percent: float)
 signal angular_velocity_changed(angular_speed: float)
 signal heading_changed(heading_degrees: float)
 signal ball_contact(intensity: float, world_position: Vector3)
+signal wall_contact(intensity: float)
 
 # Performance optimization - track last emitted values to avoid unnecessary signals
 var _last_speed: float = -1.0
@@ -415,6 +416,8 @@ func is_turbo_active() -> bool:
 
 
 func _on_body_entered(body: Node) -> void:
+	if body is StaticBody3D:
+		wall_contact.emit(clampf(linear_velocity.length() / maxf(max_speed, 0.001), 0.0, 1.0))
 	if not body is Ball:
 		return
 	var relative_speed := (linear_velocity - (body as Ball).linear_velocity).length()

Game/scripts/ship_camera.gd

@@ -97,12 +97,16 @@ func _connect_target() -> void:
 		return
 	if not target.ball_contact.is_connected(_on_target_ball_contact):
 		target.ball_contact.connect(_on_target_ball_contact)
+	if not target.wall_contact.is_connected(_on_target_wall_contact):
+		target.wall_contact.connect(_on_target_wall_contact)
 
 
 func _exit_tree() -> void:
 	AudioManager.stop_engine()
 	if is_instance_valid(target) and target.ball_contact.is_connected(_on_target_ball_contact):
 		target.ball_contact.disconnect(_on_target_ball_contact)
+	if is_instance_valid(target) and target.wall_contact.is_connected(_on_target_wall_contact):
+		target.wall_contact.disconnect(_on_target_wall_contact)
 
 
 func _input(event):
@@ -243,6 +247,10 @@ func _on_target_ball_contact(intensity: float, _world_position: Vector3) -> void
 	impact_feedback.emit(intensity)
 
 
+func _on_target_wall_contact(intensity: float) -> void:
+	AudioManager.play_wall_scrape(intensity)
+
+
 func _apply_shake(delta: float) -> void:
 	if _shake_strength <= 0.001:
 		_shake_strength = 0.0