feat(mvp): phase 4 - app registry & healthcheck

Add app CRUD API endpoints, healthcheck service with node-cron scheduler,
icon resolver (Lucide, Simple Icons, CDN, uploads), app management UI
with Superforms, health badge component, and Docker health endpoint.

plans/mvp-web-app-launcher/CONTEXT.md

@@ -2,6 +2,8 @@
 
 ## Current State
 
+Phase 4 (App Registry & Healthcheck) is complete. All app CRUD API routes are implemented at `/api/apps` (GET/POST) and `/api/apps/[id]` (GET/PATCH/DELETE) with Zod validation and auth middleware. Status history is served from `/api/apps/[id]/status`. The healthcheck service performs HTTP HEAD/GET requests with AbortController timeouts, mapping responses to online/offline/degraded/unknown. The scheduler uses node-cron (default: every 60 seconds) with an initial delayed check on startup. Icon resolution supports lucide, simple-icons (CDN), direct URL, and emoji types. The app registry UI at `/apps` renders cards in a responsive grid with category filtering and an inline Superforms create form. Custom icon uploads are handled at `/api/uploads` with type (SVG/PNG/JPG/WebP) and size (<1MB) validation, saving to `static/uploads/`. A Docker healthcheck endpoint at `/api/health` returns 200 with no auth. All Svelte components use runes mode ($state, $derived, $props).
+
 Phase 3 (Authentication System) is complete. The full local authentication flow is implemented: login, registration, logout, and JWT token refresh. `hooks.server.ts` validates access tokens on every request, injects `event.locals.user`/`session`, and silently rotates expired tokens via refresh tokens. Protected routes redirect to `/login`; guest-accessible board routes are exempt. Login and registration pages use Superforms + Zod with inline validation errors. Registration respects the `SystemSettings.registrationEnabled` toggle. Reusable middleware helpers (`requireAuth`, `requireAdmin`, `requireRole`) are available for downstream phases. The root layout injects user session into all page data. The root page redirects to the default board or login. `jwt.ts` and `password.ts` are thin re-exports from `authService` (no duplication). Build does not pass yet (Big Bang strategy — expected).
 
 ## Temporary Workarounds