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

CONTRIBUTING.md

@@ -0,0 +1,9 @@
+# Contributing
+
+Thank you for considering contributing!
+
+- Please follow the project coding style and directory structure.
+- Submit issues or pull requests for bugs, features, or improvements.
+- Add tests for new features where possible.
+- Ensure your code builds and passes tests before submitting.
+- Contributions are licensed under CC BY-SA 4.0.