feat: add PNG decoder, query3/4, Capsule+GJK/EPA, friction, Lua engine API

- PNG decoder with self-contained Deflate decompressor (RGB/RGBA)
- ECS query3 and query4 for multi-component queries
- Capsule collider + GJK/EPA narrow phase for convex shapes
- Coulomb friction in physics solver
- Lua engine API bindings (spawn, position, entity_count)

Tests: 255 → 286 (+31)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/settings.local.json

@@ -47,7 +47,9 @@
       "Read(//c/tmp/**)",
       "Bash(tar xzf:*)",
       "Bash(cp lua-5.4.7/src/*.c lua-5.4.7/src/*.h C:/Users/SSAFY/Desktop/projects/voltex/crates/voltex_script/lua/)",
-      "Bash(cd:*)"
+      "Bash(cd:*)",
+      "Bash(git status:*)",
+      "Bash(git push:*)"
     ]
   }
 }