feat: self-contained Docker installer with web setup wizard

- settings.ts: persistent settings.json in data volume (survives restarts)
- /api/setup: POST to save API_BASE_URL, API_KEY, WEB_PASSWORD, WEBHOOK_SECRET
- /setup: web-based setup wizard for first-time configuration
- /api/health: JSON health check endpoint for Docker healthcheck
- api.ts: dynamic API_BASE_URL/API_KEY resolution from settings
- login route: fallback WEB_PASSWORD from settings.json
- middleware: /setup and /api/setup are public paths
- Dockerfile: HEALTHCHECK instruction
- docker-compose.yml: healthcheck + optional .env file
- .env.example: full documentation of all env vars
- install.sh: single-command VPS installer (clone, build, run)

src/middleware.ts

@@ -5,10 +5,13 @@ const publicPaths = [
   "/login",
   "/api/auth/login",
   "/api/auth/logout",
+  "/api/health",
   "/api/proxy/health",
   "/api/posts",
   "/api/cover",
   "/api/cron",
+  "/api/setup",
+  "/setup",
   "/_next",
   "/favicon.ico",
   "/fonts",