feat(FN-007): implement repository connection API and git operations

- Add GitHubAdapter and GitLabAdapter with URL parsing
- Create provider factory in apps/api/app/git/providers/
- Implement clone, fetch, push in LocalGitOperations
- Add repository_connections router with CRUD and SSH key endpoints
- Create RepositoryConnection schema with validation
- Update models and routers __init__.py for new components
- Add comprehensive tests for git operations

apps/api/app/models/__init__.py

@@ -1,6 +1,7 @@
 from app.models.access_route import AccessRoute
 from app.models.base import Base
 from app.models.config import Config
+from app.models.credential import Credential
 from app.models.project import Project
 from app.models.repository import Repository
 from app.models.repository_connection import RepositoryConnection
@@ -14,6 +15,7 @@ __all__ = [
     "Base",
     "AccessRoute",
     "Config",
+    "Credential",
     "Project",
     "Repository",
     "RepositoryConnection",