docs: add comprehensive commit convention guide

.github/COMMIT_CONVENTION.md

@@ -0,0 +1,89 @@
+# Commit Convention Guide
+
+This project uses [Conventional Commits](https://www.conventionalcommits.org/) with [changelogen](https://github.com/unjs/changelogen) for automatic changelog generation.
+
+## Commit Message Format
+
+```
+<type>[optional scope]: <description>
+
+[optional body]
+
+[optional footer(s)]
+```
+
+## Types
+
+| Type | Emoji | Description | Version Bump |
+|------|-------|-------------|--------------|
+| `feat` | 🚀 | New features | minor |
+| `fix` | 🐛 | Bug fixes | patch |
+| `docs` | 📖 | Documentation changes | patch |
+| `style` | 💄 | Code style changes | patch |
+| `refactor` | ♻️ | Code refactoring | patch |
+| `perf` | ⚡ | Performance improvements | patch |
+| `test` | ✅ | Adding tests | patch |
+| `build` | 🏗️ | Build system changes | patch |
+| `ci` | 🤖 | CI/CD changes | patch |
+| `chore` | 🧹 | Maintenance tasks | patch |
+| `revert` | ⏪ | Reverting changes | patch |
+
+## Examples
+
+### Feature
+```bash
+git commit -m "feat: add user authentication system"
+```
+
+### Bug Fix
+```bash
+git commit -m "fix: resolve login validation error"
+```
+
+### Breaking Change
+```bash
+git commit -m "feat: redesign API structure
+
+BREAKING CHANGE: API endpoints have changed from /api/v1 to /api/v2"
+```
+
+### With Scope
+```bash
+git commit -m "feat(theme): add dark mode support"
+```
+
+## Changelog Scripts
+
+### Generate Changelog
+```bash
+pnpm run changelog
+```
+
+### Release with Changelog
+```bash
+pnpm run changelog:release
+```
+
+### Full Release Workflow
+```bash
+pnpm run release
+```
+
+## Best Practices
+
+1. **Use present tense**: "add feature" not "added feature"
+2. **Use imperative mood**: "fix bug" not "fixes bug"
+3. **Keep first line under 72 characters**
+4. **Reference issues**: "fix: resolve login issue (#123)"
+5. **Include breaking changes**: Always document breaking changes in footer
+6. **Be descriptive**: Explain what and why, not how
+
+## Scopes (Optional)
+
+Common scopes for this project:
+- `theme` - Theme system changes
+- `eslint` - ESLint configuration
+- `ui` - User interface components
+- `auth` - Authentication system
+- `electron` - Electron-specific changes
+- `build` - Build system changes