feat: Fortnite-style OTS camera + Alt free-look orbit in third person

- Third-person camera chain is now HeadPivot > OrbitPivot > ShoulderOffset
  (0.55m right, 0.12m up) > SpringArm(2.6m, 14 deg) — the character sits
  slightly left of screen centre over-the-shoulder instead of dead centre
  behind. Aim is unchanged (still the first-person camera).
- Hold Alt in third person to orbit the camera freely around the character
  with the mouse (yaw wraps, pitch clamped -69..+29 deg); the character
  keeps facing and aiming where it was. Release Alt and the camera springs
  back behind the shoulder.
- debug/orbit_capture.gd: screenshots the OTS framing, a driven orbit, and
  the spring-back for visual regression.

Co-Authored-By: Claude Fable 5 <[email protected]>

characters/player/fps_camera_rig.gd

@@ -28,6 +28,14 @@ var _pitch_impulse: float = 0.0     # extra camera pitch in radians, decays
 var _dash_fov_kick: float = 0.0     # extra FOV from dashing, decays
 var _machine: MovementStateMachine = null
 
+# Third-person free-look: hold Alt to orbit the camera around the character
+# without turning the character or aim; release and it springs back behind.
+var _orbit_yaw: float = 0.0
+var _orbit_pitch: float = 0.0
+const ORBIT_PITCH_MIN := -1.2       # radians (looking down from above)
+const ORBIT_PITCH_MAX := 0.5        # radians (looking up from below)
+const ORBIT_RETURN_SPEED := 10.0
+
 
 func _ready() -> void:
 	Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED)
@@ -71,10 +79,17 @@ func _input(event: InputEvent) -> void:
 	if event is InputEventMouseMotion and Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED:
 		var is_ads = camera and camera.fov < SettingsManager.world_fov - 5.0
 		var sens = SettingsManager.ads_sensitivity if is_ads else SettingsManager.mouse_sensitivity
-		# Yaw: rotate the player (parent)
-		get_parent().rotate_y(-event.relative.x * sens)
-		# Pitch: rotate this pivot
-		rotation.x = clampf(rotation.x - event.relative.y * sens, deg_to_rad(-pitch_limit), deg_to_rad(pitch_limit))
+		if _free_looking():
+			# Alt held in third person: orbit the camera around the character;
+			# the character keeps facing (and aiming) where it was.
+			_orbit_yaw = wrapf(_orbit_yaw - event.relative.x * sens, -PI, PI)
+			_orbit_pitch = clampf(_orbit_pitch - event.relative.y * sens,
+				ORBIT_PITCH_MIN, ORBIT_PITCH_MAX)
+		else:
+			# Yaw: rotate the player (parent)
+			get_parent().rotate_y(-event.relative.x * sens)
+			# Pitch: rotate this pivot
+			rotation.x = clampf(rotation.x - event.relative.y * sens, deg_to_rad(-pitch_limit), deg_to_rad(pitch_limit))
 
 	# Toggle mouse capture with Escape
 	if event is InputEventKey and event.pressed and event.keycode == KEY_ESCAPE:
@@ -84,6 +99,14 @@ func _input(event: InputEvent) -> void:
 			Input.set_mouse_mode(Input.MOUSE_MODE_CAPTURED)
 
 
+## True while the player is holding Alt to look around in third person.
+func _free_looking() -> bool:
+	var p := get_parent()
+	return p != null and "third_person" in p and p.third_person \
+		and Input.is_key_pressed(KEY_ALT) \
+		and Input.get_mouse_mode() == Input.MOUSE_MODE_CAPTURED
+
+
 func _process(delta: float) -> void:
 	if not camera or not params:
 		return
@@ -92,6 +115,16 @@ func _process(delta: float) -> void:
 	if not player:
 		return
 
+	# ── Third-person free-look orbit ──────────────────────────────────────
+	var orbit := get_node_or_null("OrbitPivot")
+	if orbit:
+		if not _free_looking():
+			# Spring back behind the character once Alt is released.
+			var t := 1.0 - exp(-ORBIT_RETURN_SPEED * delta)
+			_orbit_yaw = lerpf(_orbit_yaw, 0.0, t)
+			_orbit_pitch = lerpf(_orbit_pitch, 0.0, t)
+		orbit.rotation = Vector3(_orbit_pitch, _orbit_yaw, 0.0)
+
 	if not _machine:
 		_connect_machine()