Add initial project structure with Rust Nix flake template

- Create .envrc for Direnv configuration
- Add .pre-commit-config.yaml for pre-commit hooks
- Include CONTRIBUTING.md for contribution guidelines
- Initialize Cargo.toml for Rust package configuration
- Update LICENSE to link to full license text
- Create Makefile for build, run, test, and clean commands
- Revise README.md for project description and usage instructions
- Implement default Nix flake configuration in flake.nix
- Add Flatpak manifest for packaging
- Set up project metadata in project.toml
- Create shell.nix for legacy shell support
- Add skeletal Rust application in src/main.rs
- Include sample test in tests/sample_test.rs

default.nix

@@ -0,0 +1,29 @@
+{ pkgs }:
+let
+  lib = pkgs.lib;
+  templateName = builtins.baseNameOf (toString ./.);
+in
+{
+  ${templateName} = pkgs.stdenvNoCC.mkDerivation {
+    pname = templateName;
+    version = "0.1.0";
+    src = ./.;
+    dontBuild = true;
+    installPhase = ''
+      mkdir -p $out/share/${templateName}
+      if [ -d src ]; then
+        cp -r src $out/share/${templateName}/
+      fi
+      for f in README.md project.toml flake.nix default.nix shell.nix Makefile .editorconfig .gitignore; do
+        if [ -f "$f" ]; then
+          cp "$f" $out/share/${templateName}/
+        fi
+      done
+    '';
+    meta = with lib; {
+      description = "Template project: ${templateName}";
+      license = licenses.unfreeRedistributable;
+      platforms = platforms.all;
+    };
+  };
+}