Add contributing guidelines

CONTRIBUTING.md

@@ -0,0 +1,73 @@
+# Contributing to MPC
+
+## Reporting Issues
+
+- Check existing issues before creating duplicates
+- Include minimal reproduction case
+- Specify platform, compiler, and MPC version
+- Provide relevant code snippets and error output
+
+## Pull Request Process
+
+1. Fork the repository to your GitHub account
+2. Clone your fork locally:
+
+```bash
+   git clone https://github.com/yourusername/mpc.git
+   cd mpc
+```
+
+3. Add upstream remote:
+
+```bash
+   git remote add upstream https://github.com/orangeduck/mpc.git
+```
+
+4. Create a branch for your changes:
+
+```bash
+   git checkout -b fix/descriptive-name
+```
+
+5. Make your changes
+6. Test thoroughly on your platform
+7. Commit with clear, imperative messages:
+
+```bash
+   git commit -m "Fix segfault in mpc_parse cleanup"
+```
+
+8. Rebase on latest upstream before pushing:
+
+```bash
+   git fetch upstream
+   git rebase upstream/master
+```
+
+9. Push to your fork:
+
+```bash
+   git push origin fix/descriptive-name
+```
+
+10. Open pull request from your branch to `orangeduck/mpc:master`
+
+## Branch Naming
+
+- `fix/` - Bug fixes
+- `feature/` - New functionality
+- `docs/` - Documentation changes
+
+## Code Standards
+
+- Match existing code style
+- Single responsibility per commit
+- No unrelated changes in PRs
+- Include test cases when applicable
+
+## Testing
+
+- Compile without warnings
+- Run existing tests if present
+- Verify your fix resolves the reported issue
+- Test on multiple compilers if possible (gcc, clang, msvc)