feat(goals): add cinematic celebration sequence

Game/scripts/game_mode.gd

@@ -20,6 +20,13 @@ var _ship_spawn_transforms := {}
 var _hit_stop_generation := 0
 var _hit_stop_active := false
 var _time_scale_before_hit_stop := 1.0
+var _camera_rig: ShipCameraRig
+var _goal_slowmo_active := false
+var _time_scale_before_goal := 1.0
+var _goal_in_progress := false
+
+const GOAL_CELEBRATION_SECONDS := 1.6
+const GOAL_SLOWMO_SCALE := 0.22
 
 # Shared by modes that keep score (Match, Spectate); Free Play never
 # references this or emits a score_changed signal, and HUDController relies
@@ -66,16 +73,58 @@ func _on_goal_scored(_conceding_team: int) -> void:
 	pass
 
 
+# Virtual: immediate, non-presentational consequences at sensor time. Modes
+# with a score/clock override this so a last-second goal is authoritative
+# before the cinematic; reset/kickoff remains in _on_goal_scored afterwards.
+func _on_goal_registered(_conceding_team: int) -> void:
+	pass
+
+
 # Debounce: a fast ball can re-trigger the goal area before the deferred
 # reset teleports it away, which would double-count the goal.
-var _goal_cooldown := false
-
 func _handle_goal_scored(conceding_team: int) -> void:
-	if _goal_cooldown:
+	if _goal_in_progress:
 		return
-	_goal_cooldown = true
-	get_tree().create_timer(0.5).timeout.connect(func(): _goal_cooldown = false)
-	_on_goal_scored(conceding_team)
+	_goal_in_progress = true
+	_on_goal_registered(conceding_team)
+	await _play_goal_celebration(1 - conceding_team, conceding_team)
+	await _on_goal_scored(conceding_team)
+	_goal_in_progress = false
+
+
+func _play_goal_celebration(scoring_team: int, conceding_team: int) -> void:
+	# Training/headless modes never spawn a camera or HUD and must not pay a
+	# real-time presentation delay between episodes.
+	if DisplayServer.get_name() == "headless" or not is_instance_valid(_camera_rig):
+		return
+	_restore_hit_stop()
+	_goal_slowmo_active = true
+	_time_scale_before_goal = Engine.time_scale
+	Engine.time_scale = minf(Engine.time_scale, GOAL_SLOWMO_SCALE)
+	var goal_position := Vector3.ZERO
+	for goal in arena.get_goals():
+		if goal.team == conceding_team:
+			goal_position = goal.global_position
+			break
+	_camera_rig.begin_goal_cut(goal_position)
+	if hud:
+		hud.show_goal_celebration(scoring_team)
+	await get_tree().create_timer(GOAL_CELEBRATION_SECONDS, true, false, true).timeout
+	if is_instance_valid(_camera_rig):
+		_camera_rig.end_goal_cut()
+	if hud and is_instance_valid(hud):
+		hud.hide_goal_celebration()
+	# Defensive unwind: impact feedback is suppressed while goal slow-mo owns
+	# time scale, but restore any hit-stop that was already queued this frame.
+	_restore_hit_stop()
+	_restore_goal_slowmo()
+
+
+func _restore_goal_slowmo() -> void:
+	if not _goal_slowmo_active:
+		return
+	Engine.time_scale = _time_scale_before_goal
+	_goal_slowmo_active = false
 
 
 func spawn_ball() -> RigidBody3D:
@@ -104,6 +153,7 @@ func spawn_ship(team: int, spawn_index: int = 0, controller: ShipController = nu
 func spawn_camera_rig(target: Ship) -> ShipCameraRig:
 	var rig: ShipCameraRig = CAMERA_RIG_SCENE.instantiate()
 	add_child(rig)
+	_camera_rig = rig
 	rig.target = target
 	rig.impact_feedback.connect(_on_player_impact)
 	# Also wires the scene's static HUD (if any) to the same ship, rather
@@ -116,10 +166,13 @@ func spawn_camera_rig(target: Ship) -> ShipCameraRig:
 func _on_player_impact(intensity: float) -> void:
 	if hud:
 		hud.flash_impact(intensity)
-	_run_hit_stop(intensity)
+	if not _goal_slowmo_active:
+		_run_hit_stop(intensity)
 
 
 func _run_hit_stop(intensity: float) -> void:
+	if _goal_slowmo_active:
+		return
 	_hit_stop_generation += 1
 	var generation := _hit_stop_generation
 	if not _hit_stop_active:
@@ -145,6 +198,7 @@ func _restore_hit_stop() -> void:
 func _exit_tree() -> void:
 	# A scene change during the unscaled timer must never strand global time.
 	_restore_hit_stop()
+	_restore_goal_slowmo()
 
 
 # Given an already-resolved (path, reaction_ticks, action_noise) — callers