- Add GET /api/git/workspace-repos endpoint returning sub-repo list
- Add resolveGitDir() helper: resolves repoPath query param to sub-repo dir
- Update all 34 git endpoints to use resolveGitDir for workspace targeting
- Add repoPath param to 30+ frontend git API functions
- GitManagerModal: auto-detect workspace repos on mount, show repo selector
dropdown at top of sidebar, pass selected repo to all git API calls
- Auto-select first repo when workspace mode is detected
- Repo change triggers data refetch via gitRepoPath dependency