feat: add SSR and prerendering support

- Install @angular/ssr and @angular/platform-server (v21.2.x)
- Create server entry point (server.ts) and server bootstrap (main.server.ts)
- Add server routes config (app.server.routes.ts) with 5 prerendered routes:
  /, /about, /schedule, /events, /contact
- Update angular.json with server/ssr/prerender build configuration
- Add prerender-routes.txt for build-time static route generation
- Fix SSR compatibility:
  - App component: guard DOM access with isPlatformBrowser
  - StructuredDataComponent: skip head manipulation on server
  - ThemeService: skip CSS variable application on server
  - ShowService/EventService: return empty arrays on API failure
    (graceful fallback during prerender with no backend)
- Prerendered output verified: 5 static HTML routes in dist/

src/app/services/event.service.ts

@@ -1,6 +1,7 @@
 import { Injectable, inject } from '@angular/core';
 import { HttpClient, HttpParams } from '@angular/common/http';
-import { Observable } from 'rxjs';
+import { Observable, of } from 'rxjs';
+import { catchError } from 'rxjs/operators';
 
 import { Event } from '../interfaces/event';
 import { getAppConfig } from './app-config.service';
@@ -16,7 +17,12 @@ export class EventService {
   getEvents(active?: boolean): Observable<Event[]> {
     let params = new HttpParams();
     if (active !== undefined) params = params.set('active', String(active));
-    return this.http.get<Event[]>(this.baseUrl, { params });
+    return this.http.get<Event[]>(this.baseUrl, { params }).pipe(
+      catchError((err) => {
+        console.warn('EventService: Failed to load events, returning empty array.', err);
+        return of<Event[]>([]);
+      }),
+    );
   }
 
   getEvent(id: number): Observable<Event> {

src/app/services/show.service.ts

@@ -1,6 +1,7 @@
 import { Injectable, inject } from '@angular/core';
 import { HttpClient } from '@angular/common/http';
-import { Observable } from 'rxjs';
+import { Observable, of } from 'rxjs';
+import { catchError } from 'rxjs/operators';
 
 import { Show } from '../interfaces/show';
 import { getAppConfig } from './app-config.service';
@@ -41,7 +42,12 @@ export class ShowService {
   private baseUrl = `${getAppConfig().apiBaseUrl}/api/shows`;
 
   getShows(): Observable<Show[]> {
-    return this.http.get<Show[]>(this.baseUrl);
+    return this.http.get<Show[]>(this.baseUrl).pipe(
+      catchError((err) => {
+        console.warn('ShowService: Failed to load shows, returning empty array.', err);
+        return of<Show[]>([]);
+      }),
+    );
   }
 
   getShow(id: number): Observable<Show> {

src/app/services/theme.service.ts

@@ -1,4 +1,5 @@
-import { Injectable } from '@angular/core';
+import { Injectable, inject, PLATFORM_ID } from '@angular/core';
+import { isPlatformBrowser } from '@angular/common';
 
 import { StationConfig } from '../interfaces/station-config';
 
@@ -32,11 +33,16 @@ function gradient(from: string, mid: string, to: string): string {
   providedIn: 'root',
 })
 export class ThemeService {
+  private platformId = inject(PLATFORM_ID);
+
   /**
    * Apply color theme from StationConfig as CSS custom properties on `:root`.
    * Also generates derived gradient variables.
+   * Skips silently on the server (SSR) — CSS vars are set in the browser after hydration.
    */
   apply(config: StationConfig): void {
+    if (!isPlatformBrowser(this.platformId)) return;
+
     const root = document.documentElement.style;
 
     for (const { field, prop } of COLOR_MAP) {