feat: implement config profile git mounts

- Add git_mounts column to config_profiles table (JSONB)
- Create GitMount Pydantic models with validation
- Add repo validation in create/update endpoints
- Update profile resolver to merge git mounts from includes
- Implement auto-clone, branch checkout, and glob expansion
- Add parallel processing for git mount resolution
- Create GitMountEditor frontend component
- Update TypeScript types and API clients
- Add CSS styles for git mount UI
- Frontend type check and build pass

Implements tasks 1.1-7.9 of config-profile-git-mounts spec

openspec/changes/config-profile-git-mounts/proposal.md

@@ -0,0 +1,31 @@
+## Why
+
+Config profiles currently only support inline file content, which is impractical for dotfiles and configuration repositories that users manage with git. Users need a way to include files from git repositories (similar to yadm) so they can version-control their dotfiles and mount them into containers at startup.
+
+## What Changes
+
+- Add `git_mounts` field to config profiles, allowing references to git repositories
+- Mount specific paths from git repositories into containers at configurable target paths
+- Support branch/tag selection for reproducible mounts
+- Integrate with existing profile resolution and instance startup pipeline
+- Update config profile UI to manage git repository mounts alongside existing mounts
+- **No breaking changes** - existing profiles continue to work unchanged
+
+## Capabilities
+
+### New Capabilities
+- `config-profile-git-mounts`: Mounting files from git repositories into containers via config profiles, including repo selection, path mapping, and branch pinning
+
+### Modified Capabilities
+- `tool-instances`: Instance startup pipeline now processes git mounts from resolved profiles before container creation
+- `git-repo`: Repository model may need branch/tag listing for mount configuration
+
+## Impact
+
+- **Backend**: `apps/api/src/models/config_profile.py` - add git_mounts field
+- **Backend**: `apps/api/src/services/config_profile_resolver.py` - resolve git mounts in profile resolution
+- **Backend**: `apps/api/src/services/docker.py` or instance startup - bind mount from repo path to container
+- **Backend**: `apps/api/src/api/config_profiles.py` - CRUD for git mounts
+- **Frontend**: `apps/web/src/pages/config-profiles.tsx` - UI for managing git mounts
+- **Frontend**: `apps/web/src/api/config_profiles.ts` - API types for git mounts
+- **Database**: Migration to add git_mounts column to config_profiles table