feat: real per-weapon reload/recoil choreography + knife slash, fully matte hair

Weapons no longer reload by spinning the gun 360 (that was the upside-down
flip; nothing detached). New ViewmodelAnim module drives per-style manual-of-
arms sequences on the existing model_root + named arm pivots, with a temporary
magazine/shell/rocket/cell prop that visibly leaves and returns to the gun:

  - mag     (M4/AK/MP7/DMR): roll gun to present the well, hand rips the mag
            down and away, fresh mag up, seat, charge. Gun stays UPRIGHT.
  - boltmag (AWP): mag swap + a distinct bolt-cycle rock.
  - break   (double barrel): hinge open, flick both shells out, drop fresh
            shells in, snap shut.
  - tube    (rocket launcher): tip the tube in, shove a rocket home, shoulder.
  - cell    (plasma/nail gun): glowing energy cell swapped on the side.

Per-shot viewmodel recoil kick (ViewmodelAnim.apply_kick) scaled by each
weapon's recoil_amplitude, so an AWP slams and an MP7 chatters — replaces the
old flat model behaviour. Weapons expose reload_style; base classes call
play_reload / stop (on unequip) / apply_kick.

Knife: the old barely-visible flick is now a real diagonal slash that
alternates backhand/forehand, whips the blade through screen centre, and
fires the third-person melee arm-swing action (synced to other players).

Hair/materials: specular fully to 0 (even a 2% stepped glint swept as shine
across Taila's hair when the camera moved); rim trimmed to a whisper. Fully
matte cloth/hair now.

Verify: debug/fp_weapon_capture.gd screenshots each weapon's reload phases,
the knife slash, and the fire kick.

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

weapons/weapon_manager.gd

@@ -272,15 +272,16 @@ func _set_layer_recursive(node: Node, layer_mask: int) -> void:
 		_set_layer_recursive(child, layer_mask)
 
 func _add_procedural_arms(weapon: Node3D) -> void:
-	# Attach to weapon instead of model_root to avoid arms spinning on reload
-	_build_arm(weapon, Vector3(0.25, -0.3, 0.5), Vector3(0.04, -0.05, 0.05))
+	# Attach to weapon instead of model_root so reload choreography can move
+	# the gun (model_root) and each hand (named pivots) independently.
+	_build_arm(weapon, Vector3(0.25, -0.3, 0.5), Vector3(0.04, -0.05, 0.05), "ArmR")
 	if "weapon_name" in weapon and weapon.weapon_name != "Knife":
-		_build_arm(weapon, Vector3(-0.25, -0.3, 0.4), Vector3(-0.02, -0.02, -0.3))
+		_build_arm(weapon, Vector3(-0.25, -0.3, 0.4), Vector3(-0.02, -0.02, -0.3), "ArmL")
 
 
 ## A first-person arm styled after the character skin: dark detached sleeve,
 ## glowing cuff, bare hand — instead of the old featureless blue slab.
-func _build_arm(weapon: Node3D, shoulder: Vector3, hand: Vector3) -> void:
+func _build_arm(weapon: Node3D, shoulder: Vector3, hand: Vector3, arm_name: String = "") -> void:
 	var sleeve_mat = StandardMaterial3D.new()
 	sleeve_mat.albedo_color = Color(0.10, 0.11, 0.14)  # near-black sleeve
 	sleeve_mat.roughness = 0.8
@@ -293,6 +294,8 @@ func _build_arm(weapon: Node3D, shoulder: Vector3, hand: Vector3) -> void:
 	skin_mat.roughness = 0.9
 
 	var pivot = Node3D.new()
+	if arm_name != "":
+		pivot.name = arm_name
 	pivot.position = shoulder
 	pivot.look_at_from_position(shoulder, hand, Vector3.UP)