feat: implement tool types definition system

- Add ToolType SQLAlchemy model with Docker Compose template support
- Create CRUD API endpoints for tool type management
- Implement YAML and template variable validation
- Add built-in tool types (code-server, jupyter-notebook) seeded on startup
- Create frontend page with list, create, edit, and delete functionality
- Add tool types navigation to app shell
- Update mypy config to ignore missing imports

Quality gates: ruff (passed), mypy (passed), pytest unit (8 passed),
typecheck (passed), lint (passed), build (passed)

apps/web/src/components/app-shell.tsx

@@ -7,6 +7,7 @@ const NAV_ITEMS = [
   { to: "/", label: "Dashboard" },
   { to: "/projects", label: "Projects" },
   { to: "/ssh-keys", label: "SSH Keys" },
+  { to: "/tool-types", label: "Tool Types" },
   { to: "/settings", label: "Settings" }
 ];