Initial commit: rust-craft plugin

Rust-on-NixOS knowledge plugin. Relocates plugin.json into .claude-plugin/
so it loads as a proper plugin, and adds README/LICENSE/.gitignore for
distribution. Skill rust-nix-toolchain (Cranelift vs LLVM codegen, fenix
nightly pins, cargo/clippy gates) with cranelift-limitations reference.

.claude-plugin/plugin.json

@@ -0,0 +1,21 @@
+{
+	"name": "rust-craft",
+	"version": "1.0.0",
+	"description": "Rust development on NixOS — toolchain management (fenix nightly pins), codegen backends (Cranelift vs LLVM), clippy/cargo quality-gate workflows, and common pitfalls.",
+	"author": {
+		"name": "oleks",
+		"email": "plugins@oleks.space"
+	},
+	"repository": "https://claude-plugins.oleks.space/plugins/rust-craft.git",
+	"license": "MIT",
+	"keywords": [
+		"rust",
+		"nixos",
+		"fenix",
+		"cranelift",
+		"llvm",
+		"clippy",
+		"cargo",
+		"toolchain"
+	]
+}