feat: add repository workspace as default project view
- Create git file utilities (list_tree, get_file_content, list_branches, commit_file)
- Add file browsing API endpoints (list, content, branches, update)
- Create RepoWorkspace page with sidebar + main content layout
- Add FileTree component with directory navigation
- Add FileViewer component for viewing file contents
- Update project list to link to workspace
- Add workspace CSS styles
- Update router with workspace route
Quality gates: ruff ✓, mypy ✓, typecheck ✓, build ✓
Fusion
6807f449b7