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]>

weapons/weapon_manager.gd

@@ -41,11 +41,13 @@ func _setup_viewmodel_viewport() -> void:
 	sub_viewport.transparent_bg = true
 	# Shared world so it renders main scene's objects that have layer 20
 	# (In Godot 4, own_world_3d is false by default, but let's be explicit)
-	sub_viewport.own_world_3d = false 
+	sub_viewport.own_world_3d = false
+	sub_viewport.msaa_3d = Viewport.MSAA_4X # keep ink outlines crisp on the viewmodel
 	sv_container.add_child(sub_viewport)
-	
+
 	vm_camera = Camera3D.new()
 	vm_camera.cull_mask = 1 << 19 # Only see layer 20
+	vm_camera.near = 0.01 # viewmodel sits close to the lens; avoid clipping
 	sub_viewport.add_child(vm_camera)
 	
 	# Add a light specifically for the viewmodel in case main lights don't reach
@@ -231,7 +233,12 @@ func _spawn_weapon(slot: int, weapon_id: String) -> void:
 		w.set_meta("script_path", script_path)
 		
 		_add_procedural_arms(w)
-		
+
+		# Cel-shade the view model + arms so the first-person weapon matches
+		# the world's look. No inverted-hull outline: FBX weapon models have
+		# hard-edged normals that make the hull tear into scratchy artifacts.
+		LevelMaterials.apply_toon_recursive(w, 0.0)
+
 		# Set weapons to viewmodel layer
 		_set_layer_recursive(w, 1 << 19)