feat: shooter animation feel — directional lean, slide, composed airborne, weapon hold

Layer a procedural SkeletonModifier3D (ShooterPoseModifier) on top of the base
clip so the character reads like a movement-shooter avatar:

- Directional lean: banks into the movement direction (right/left/back) and
  blends smoothly for diagonals, driven by velocity relative to facing.
- Slide: leans the torso back and pitches the head up to look forward, instead
  of the base clip's forward-torso/legs-out "spine break".
- Airborne: plays a composed Jump pose (weapon ready) rather than a flailing
  fall.
- Weapon hold: the base clip already keeps the arms down (weapon at the hip);
  on ADS both arms lift and swing in toward centre-front to aim. ADS is read
  from the active weapon and synced (synced_is_ads) so remote players raise
  their weapons too.

The controller feeds movement direction + ADS to SkinnedPlayerModel.set_locomotion()
each frame (works for local and remote via synced velocity/rotation). All
rotations are authored in skeleton space (fwd=+Z, up=+Y, right=-X) and converted
per-bone; tuning constants are at the top of ShooterPoseModifier.

Verified by rendering the poses (idle/strafe/back/slide/ads) in a real Godot
viewport. Smoke test 30/30.

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

movement/player_movement_controller.gd

@@ -73,6 +73,7 @@ var synced_movement_speed: float = 0.0
 var synced_is_crouching: bool = false
 var synced_position: Vector3 = Vector3.ZERO
 var synced_velocity: Vector3 = Vector3.ZERO
+var synced_is_ads: bool = false
 @export var synced_skin_id: String = ""
 @export var synced_weapon_path: String = ""
 
@@ -864,11 +865,17 @@ func _physics_process(_delta: float) -> void:
 	else:
 		grapple_swing_player.volume_db = lerpf(grapple_swing_player.volume_db, -80.0, _delta * 15.0)
 
+	# Local player's aim-down-sights state (drives the model's weapon raise).
+	synced_is_ads = _read_ads()
+
 	# Drive the visual model (skinned GLB or procedural) from local state
 	var visual = get_visual_model()
 	if visual:
 		var h_speed = Vector2(velocity.x, velocity.z).length()
 		visual.update_state(sm.current_state, h_speed, sm.input_crouch)
+		if visual.has_method("set_locomotion"):
+			var d := _local_move_dir()
+			visual.set_locomotion(d.x, d.y, 1.0 if synced_is_ads else 0.0)
 
 	# Publish state for remote peers
 	synced_movement_state = sm.current_state
@@ -878,6 +885,28 @@ func _physics_process(_delta: float) -> void:
 	synced_velocity = velocity
 
 
+## Movement direction relative to facing: x = strafe (+right), y = forward
+## (+forward). Derived from velocity so it works for local and remote players.
+func _local_move_dir() -> Vector2:
+	var hspeed := Vector2(velocity.x, velocity.z).length()
+	if hspeed < 0.5:
+		return Vector2.ZERO
+	var local_vel := global_transform.basis.inverse() * velocity
+	return Vector2(local_vel.x / hspeed, -local_vel.z / hspeed)
+
+
+## Whether the local player's active weapon is aiming down sights.
+func _read_ads() -> bool:
+	if not is_instance_valid(camera):
+		return false
+	var wman = camera.get_node_or_null("WeaponManager")
+	if wman and "active_slot" in wman and wman.weapons.has(wman.active_slot):
+		var w = wman.weapons[wman.active_slot]
+		if w and "is_ads" in w:
+			return w.is_ads
+	return false
+
+
 func _on_movement_event(ev: String, data: Dictionary) -> void:
 	if ev == "chain_updated":
 		chain_updated.emit(data.count, data.bonus)
@@ -914,6 +943,9 @@ func _process(delta: float) -> void:
 		var visual = get_visual_model()
 		if visual:
 			visual.update_state(synced_movement_state, synced_movement_speed, synced_is_crouching)
+			if visual.has_method("set_locomotion"):
+				var d := _local_move_dir()
+				visual.set_locomotion(d.x, d.y, 1.0 if synced_is_ads else 0.0)
 			# Check for weapon changes
 			if synced_weapon_path != "" and synced_weapon_path != visual.get_meta("current_weapon_path", ""):
 				visual.set_weapon(synced_weapon_path)