feat: implement git repository management

- Add backend API for git repository CRUD (create, list, delete)
- Support bare repository initialization and mirror cloning
- Add cascade delete for repositories when project is deleted
- Add frontend page for repository management per project
- Update project page with link to repositories
- Add repo_base_path to config
- Quality gates: ruff, mypy, typecheck, lint, build all pass

apps/api/src/config.py

@@ -45,6 +45,9 @@ class Settings(BaseSettings):
     access_token_ttl_minutes: int = 15
     refresh_token_ttl_days: int = 7
 
+    # Repository storage
+    repo_base_path: str = "/data/repos"
+
     model_config = SettingsConfigDict(env_file=".env", extra="ignore", populate_by_name=True)
 
     @property