feat: complete workspace-first-ui cleanup and tests

- Delete dead repo-workspace code: RepoWorkspacePage, useRepoWorkspace,
  WorkspaceLayout, FileBrowser, old git components (git-toolbar, file-editor,
  commit-panel), and repo-workspace.css.
- Fix stale backend test imports for moved models/services.
- Add GitOperations unit tests.
- Add integration tests for workspace files, git, and instances endpoints.
- Add frontend tests for WorkspaceDetailPage and ProjectCard.
- Update OpenSpec workspace-first-ui tasks and mark change completed.
- Regenerate project maps.

Quality gates: npm run typecheck, npm run lint, npm test -- --run (87 passed),
python3 -m py_compile on changed backend files, pytest backend workspace tests.

apps/api/.pi-map.md

@@ -4,7 +4,7 @@ dir: apps/api
 index: apps/api/.pi-map.index.md
 
 ## role
-Backend API server providing project management, git repository operations, and development tool orchestration via Docker containers.
+Self-hosted FastAPI backend API that manages projects, git repositories, and development tools via Docker instances.
 ## files
 - .dockerignore | Specifies files and directories to exclude from Docker build context to reduce image size and avoid copying unnecessary files into containers. | dep: Docker
 - Dockerfile | Multi-stage Docker build for a Python application with Docker socket access, Cloudflare tunneling, and database dependency waiting | dep: python:3.11-slim, gcc, libpq-dev, docker-ce-cli, docker-compose-plugin, cloudflared, uvicorn, pyproject.toml dependencies
@@ -14,7 +14,7 @@ Backend API server providing project management, git repository operations, and
 - uv.lock | Lock file for the uv Python package manager that pins exact dependency versions and their artifact hashes for reproducible installations | dep: uv, Python 3.11+, aiosqlite, alembic, annotated-doc, annotated-types, anyio, ast-serialize, asyncpg, and many other PyPI packages
 - wait-for-db.sh | Wait for a PostgreSQL database to become available before executing a command, with configurable retry logic. | dep: nc (netcat), sh (POSIX shell), sleep
 ## arch
-FastAPI-based async Python service with multi-stage Docker deployment, PostgreSQL database with Alembic migrations, Cloudflare tunnel integration, and uv package management.
+Multi-stage Dockerized Python application using async FastAPI, PostgreSQL with Alembic migrations, uv package management, and Cloudflare tunneling with external Docker socket access.
 ## tags
 docker, alembic, python, database, fastapi, postgresql, asyncpg, uvicorn
 ## symbols