Consolidate raw art under art/ and prune unused assets

Group all raw art by role under art/ (characters, levels, weapons, fx,
anim, textures, ui, icons, fonts, hdri, materials), matching the earlier
code reorg. Files are snake_case; asset uids are preserved so uid:// refs
still resolve, and every res:// path reference is rewritten across scenes,
scripts and project.godot.

- Move the used assets out of Assets/ Animations/ fonts/ HUD/ HDRI/
  Materials/ into art/; remove those dirs.
- Materials snake_cased: barrel_metal, barrel_wood, bear_claw_fx, fire.
- Delete unreferenced assets: alternate models, empty stub scripts,
  superseded BEAR_*.tres, marketing/spare PNGs, a spare font weight and
  the orphan M_Barrel_wood.gdshader.
- Blender: drop .blend auto-backups and matador_v01/v02 (+ stale v02 fbx);
  keep matador_v03 and repoint create_matador_anims.py to it. .gitignore
  now blocks all Blender/*.blend[0-9] backups.
- GLB Extract-Textures siblings (art/levels/*.png) kept and tracked.
- Document the art/ layout in CLAUDE.md.

Headless suite green; menu and gameplay shell boot clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FBbGXbzg3SD6ZBSadPPF5H

art/fonts/CinzelDecorative-Bold.ttf.import

@@ -0,0 +1,36 @@
+[remap]
+
+importer="font_data_dynamic"
+type="FontFile"
+uid="uid://rcfn6xhs7fur"
+path="res://.godot/imported/CinzelDecorative-Bold.ttf-71cca077ba75a6c829f53e2548a2580d.fontdata"
+
+[deps]
+
+source_file="res://art/fonts/CinzelDecorative-Bold.ttf"
+dest_files=["res://.godot/imported/CinzelDecorative-Bold.ttf-71cca077ba75a6c829f53e2548a2580d.fontdata"]
+
+[params]
+
+Rendering=null
+antialiasing=1
+generate_mipmaps=false
+disable_embedded_bitmaps=true
+multichannel_signed_distance_field=false
+msdf_pixel_range=8
+msdf_size=48
+allow_system_fallback=true
+force_autohinter=false
+modulate_color_glyphs=false
+hinting=3
+subpixel_positioning=4
+keep_rounding_remainders=true
+oversampling=0.0
+Fallbacks=null
+fallbacks=[]
+Compress=null
+compress=true
+preload=[]
+language_support={}
+script_support={}
+opentype_features={}