fix: ensure SSR always fetches fresh assets from database

Root cause: Dockerfile copied only browser/ to nginx; server/server.mjs
was built but never deployed or executed. Prerender baked DEFAULT_CONFIG
into static HTML with no API at build time, causing stale content on
every initial paint.

Changes:
- Dockerfile: serve stage uses node:22-alpine, installs nginx via apk,
  copies both browser/ and server/ bundles from build stage
- docker-entrypoint.sh: starts Angular SSR Node process on port 4200,
  waits for readiness, exports SSR_API_BASE_URL, then exec nginx
- nginx.conf.template: adds upstream ssr_backend block (127.0.0.1:4200),
  proxies / to SSR backend, static assets served directly with 1y cache
- app.server.routes.ts: all routes switched from RenderMode.Prerender
  to RenderMode.Server for zero stale content
- server.ts: removed dead prerender code (PRERENDERED_ROUTES,
  isPrerenderedRoute, allowStaticRouteRender)
- main.server.ts: injects SSR-aware apiBaseUrl via APP_CONFIG
  (reads SSR_API_BASE_URL env var)
- server.spec.ts: updated 5 test suites + added 5 new suites (31 tests)
  covering server.ts cleanup, RenderMode.Server, entrypoint lifecycle,
  Dockerfile build, nginx upstream proxy, and API URL injection
- vitest.config.ts: added server.spec.ts to include pattern

Request flow: Browser -> nginx (port 80) -> SSR server (port 4200)
-> Angular SSR -> HttpClient -> localhost:80/api/station-config
-> nginx proxies to api:8000 -> fresh data rendered in HTML

src/main.server.ts

@@ -4,13 +4,20 @@ import { provideServerRendering, withRoutes } from '@angular/ssr';
 
 import { appConfig } from './app/app.config';
 import { App } from './app/app';
+import { APP_CONFIG, AppConfig } from './app/services/app-config.service';
 import { serverRoutes } from './app/app.server.routes';
 
+// During SSR, the API base URL must be absolute (HttpClient runs in Node.js).
+// nginx proxies /api/ to the upstream, so point at nginx (port 80) locally.
+const ssrApiBaseUrl = process.env.SSR_API_BASE_URL || 'http://localhost:80';
+const ssrAppConfig: AppConfig = { apiBaseUrl: ssrApiBaseUrl };
+
 const serverAppConfig = {
   ...appConfig,
   providers: [
     ...appConfig.providers,
     { provide: APP_ID, useValue: 'server' },
+    { provide: APP_CONFIG, useValue: ssrAppConfig },
     provideServerRendering(withRoutes(serverRoutes)),
   ],
 };