Import art/VFX asset packs + game-feel systems; normalize texture extensions to lowercase for LFS

Add BefourStudios SciFi environment packs, Gabriel Aguiar VFX, and the
ShaderCrew Toon Shader embedded packages, plus combat/enemy/wave/death
gameplay systems and supporting vault docs/screenshots.

Rename 11 vendor textures from uppercase .PNG/.HDR to lowercase so the
case-sensitive Git LFS filters (*.png/*.hdr) match on case-sensitive
filesystems (Linux CI, case-sensitive macOS), not just locally where
core.ignorecase=true masks the gap. Each .meta moved with its asset so
GUID references are preserved. All ~1000 binaries tracked via LFS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Packages/com.shadercrew.the-toon-shader.core/package.json

@@ -0,0 +1,20 @@
+{
+  "name": "com.shadercrew.the-toon-shader.core",
+  "displayName": "The Toon Shader-Core",
+  "version": "1.4.2",
+  "author": {
+    "name": "ShaderCrew",
+    "url": "https://www.shadercrew.com/",
+    "email": "support@shadercrew.com"
+  },
+  "unity": "2020.1",
+  "keywords": [
+    "Toon Shader",
+    "toon",
+    "cartoon",
+    "Shader"
+  ],
+  "type": "tool",
+  "hideInEditor": false,
+  "description": "Core functionality and shared utilities for all 2D and 3D The Toon Shader.\nIncludes base scripts, common resources, and foundational systems used by both 2D and 3D Toon Shader packages.\n\nNote: This package is a dependency for The Toon Shader-2D and The Toon Shader-3D. It is not intended for direct use in projects."
+}