Redesign teams portal and add user autocomplete for member invitations

- Redesign TeamsPage with modern card-based layout including stats bar,
  search functionality, and empty states
- Add UserAutocomplete component with debounced search and keyboard
  navigation for selecting existing users
- Add /api/v1/users/search endpoint for username prefix search
- Update TeamMembersPage to use UserAutocomplete instead of free text input

CHANGELOG.md

@@ -48,6 +48,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Team-based access displayed as read-only with "Source" column indicating origin
   - Team members with access show team slug and role
 - Added integration tests for team CRUD, membership, and project operations
+- Redesigned teams portal with modern card-based layout
+  - Card grid view with team avatar, name, slug, role badge, and stats
+  - Stats bar showing total teams, owned teams, and total projects
+  - Search functionality for filtering teams (appears when >3 teams)
+  - Empty states for no teams and no search results
+- Added user autocomplete component for team member invitations
+  - `GET /api/v1/users/search` endpoint for username prefix search
+  - Dropdown shows matching users as you type
+  - Keyboard navigation support (arrow keys, enter, escape)
+  - Debounced search to reduce API calls
 - Added unit tests for TeamAuthorizationService
 - Added `ORCHARD_ADMIN_PASSWORD` environment variable to configure initial admin password (#87)
   - When set, admin user is created with the specified password (no password change required)