feat: cel-shaded look & feel overhaul — real audio, comic UI, themed VFX

Audio (all CC0 — Kenney packs + OpenGameArt, see assets/sounds/SOURCES.md):
- Replace every procedural synth WAV with forged sounds (ffmpeg pitch/layer
  mixes): distinct fire sounds per weapon with 2-3 variations, explosions,
  footsteps x5, land/jump/dash/vault, knife swing, hit/kill confirms,
  bullet impacts, reload, flight loops, UI hover/click/confirm/error,
  match jingles, menu music
- AudioManager.stream_for(): AudioStreamRandomizer per sound id — every
  weapon now gets variation + pitch randomization on each shot
- Explosions and bullet impacts play positional audio; landing has its own
  sound instead of a pitched footstep; ambient wind bed on every map

Visuals:
- ExplosionVFX: shared cel-shaded burst (white-hot stepped core, ink
  shockwave ring, star spikes, flat smoke puffs) replaces the orange
  sphere in both local and remote-replay paths
- Comic star muzzle flashes on all weapons; unified cel tracer bolts with
  ink outlines across hitscan/shotgun/remote paths
- Impact decals: hard-stepped ink-splat gradients instead of soft airbrush
- Toon shading on first-person view models + arms, third-person weapons,
  and the procedural humanoid fallback (no hull outlines on FBX weapons —
  their hard normals tear the inverted hull)
- Fix: giant soft "blob" highlight on floors — toon rim/specular disabled
  on level-geometry materials (pre-existing artifact since the cel commit)
- Fix: own third-person weapon rendered into the first-person camera
  (shadows-only now covers first_person_mode)

UI:
- UITheme: comic theme on the root window — Bangers display font (OFL),
  paper panels with thick ink borders + hard drop shadows, papaya accent,
  themed buttons/inputs/popups; hover/click sounds on all menu buttons
- Main menu: tilted comic wordmark, sunset toon diorama, looping menu music
- Match HUD: themed scoreboard/killfeed/kill counter

Viewports:
- 4x MSAA project-wide + viewmodel/diorama viewports (crisp ink lines)
- Viewmodel camera near plane 0.01; third-person camera FOV syncs settings
- debug/visual_capture.gd: dev tool to screenshot menu + level for review

Verified: 11/11 movement tests, spawn smoke test 0 failures, before/after
screenshot comparison of menu and level.

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

characters/humanoid_model.gd

@@ -163,6 +163,11 @@ func _ready() -> void:
 	calf_r.cast_shadow = shadow_setting
 	calf_r_pivot.add_child(calf_r)
 
+	# Cel-shade + ink outline the blocky fallback body so it matches skinned
+	# player models (shadows-only bodies skip it: outlines would cast shadows)
+	if not shadows_only:
+		LevelMaterials.apply_toon_recursive(root_pivot, 0.012)
+
 ## Skin System
 var current_skin: PlayerSkin
 var skin_model: Node3D
@@ -222,6 +227,9 @@ func _apply_color(col: Color) -> void:
 		hmat.albedo_color = Color(0.95, 0.85, 0.78)
 		hmat.roughness = 0.8
 		head.mesh.material = hmat
+	# Re-toon after the material swap (fresh StandardMaterials above)
+	if not shadows_only:
+		LevelMaterials.apply_toon_recursive(root_pivot, 0.012)
 
 func update_state(state: String, speed: float, is_crouching: bool = false) -> void:
 	current_state = state
@@ -257,7 +265,10 @@ func set_weapon(script_path: String) -> void:
 		w.set_process_input(false)
 		if shadows_only:
 			_set_shadows_recursive(w)
-			
+		else:
+			# Toon shading only — FBX weapon normals tear inverted-hull outlines
+			LevelMaterials.apply_toon_recursive(w, 0.0)
+
 		# Force position after the weapon's _build_model() sets it for 1st person
 		w.position = Vector3(-0.15, 1.0, 0.4)
 		w.rotation_degrees = Vector3(0, 180, 0)

characters/skinned_player_model.gd

@@ -353,7 +353,10 @@ func set_weapon(script_path: String) -> void:
 	w.ready.connect(func():
 		w.set_process(false)
 		w.set_process_input(false)
-		if shadows_only:
+		# Owner's first-person view must not see their own held weapon (it
+		# sits right in front of the lens as a huge blob) — shadows only,
+		# same as the body. set_owner_visible reveals it in third person.
+		if shadows_only or first_person_mode:
 			_set_shadows_recursive(w)
 		# Undo the first-person viewmodel placement from the weapon's _ready.
 		w.position = Vector3(0.0, 0.08, 0.03)