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/plasma_gun.gd

@@ -3,6 +3,7 @@ class_name PlasmaGun
 
 func _init() -> void:
 	weapon_name = "Plasma Gun"
+	reload_style = "cell"
 	fire_rate = 0.15 # Moderate
 	max_ammo = 25
 	reload_time = 1.8