feat(gitea): implement gitea_coder role with scope enforcement (#20)
## Summary
Implements the gitea_coder role as defined in issue #11, providing a complete workflow automation layer for Git operations with scope enforcement.
## Features
### Branch Management with Scope Gating
- ✅ Enforces branch naming conventions (feature/, fix/, refactor/, docs/, test/, chore/)
- ✅ Prevents direct pushes to protected branches (main, master, develop, dev)
- ✅ Auto-appends issue numbers to branch names
### Unified Commit Workflow
- ✅ Automatic create vs replace detection
- ✅ Conventional commits format with issue references
- ✅ Detailed commit message generation
### PR Creation
- ✅ Validates source branch is not protected
- ✅ Auto-references issues in PR description
- ✅ Uses existing gitea/dev.py operations
### Ticket Integration
- ✅ Reads and parses issue requirements
- ✅ Extracts testing criteria and technical notes
- ✅ Suggests branch names from issue content
## Files Added
- `gitea/coder.py` - Complete gitea_coder role implementation
## Files Modified
- `README.md` - Added gitea_coder documentation
## Testing Criteria
✅ Can create feature branch from ticket
✅ Can modify files according to ticket requirements
✅ Can generate commit messages with issue references
✅ Can create PR for review
Refs: #11
Reviewed-on: #20
xcaliber
889680a7b7