feat(seo): Phase 2 — route-level metadata service and JSON-LD structured data

Add SeoService for dynamic metadata management:
- Per-route document titles (e.g., 'KMountain Flower Radio — About')
- Meta descriptions from station config per route
- Canonical URLs, Open Graph tags, Twitter Card tags
- Input sanitization (HTML stripping, URL validation, attribute escaping)
- noindex robots directives for /login and /admin routes
- Centralized router watcher (zero per-component boilerplate)

Add StructuredDataService + StructuredDataComponent for JSON-LD:
- Organization schema (NCBOrganization) site-wide with contact info
- WebSite schema with publisher info
- WebPage schema per-route with breadcrumbs
- Dynamic Event schema on /events page
- RadioSeason schema on /schedule page

Wire up SeoService.watchRouter() in app-root ngOnInit.
Wire up StructuredDataComponent in app-root template.
Wire up EventsComponent and ScheduleComponent to feed data to
StructuredDataService for dynamic schema injection.

Includes full test suite for SeoService (22 tests).

src/app/app.ts

@@ -1,21 +1,22 @@
 import { Component, computed, effect, inject, OnInit, OnDestroy } from '@angular/core';
-import { Title } from '@angular/platform-browser';
 import { RouterOutlet } from '@angular/router';
 import { NavbarComponent } from './navbar/navbar.component';
 import { MediaPlayerComponent } from './media-player/media-player.component';
 import { FooterComponent } from './footer/footer.component';
+import { StructuredDataComponent } from './structured-data/structured-data.component';
 import { StationConfigService } from './services/station-config.service';
+import { SeoService } from './services/seo.service';
 
 @Component({
   selector: 'app-root',
   standalone: true,
-  imports: [RouterOutlet, NavbarComponent, MediaPlayerComponent, FooterComponent],
+  imports: [RouterOutlet, NavbarComponent, MediaPlayerComponent, FooterComponent, StructuredDataComponent],
   templateUrl: './app.html',
   styleUrl: './app.scss',
 })
 export class App implements OnInit, OnDestroy {
-  private titleService = inject(Title);
   private stationConfig = inject(StationConfigService);
+  private seoService = inject(SeoService);
 
   readonly hasStream = computed(() => {
     const cfg = this.stationConfig.config();
@@ -26,11 +27,9 @@ export class App implements OnInit, OnDestroy {
   private resizeObserver: ResizeObserver | null = null;
 
   constructor() {
+    // Update favicon when station config changes.
     effect(() => {
       const config = this.stationConfig.config();
-      const fullName = `${config.name_primary} ${config.name_secondary}`.trim();
-      this.titleService.setTitle(fullName);
-
       const faviconEl = document.querySelector('link[rel="icon"]') as HTMLLinkElement | null;
       if (faviconEl && config.logo_url) {
         faviconEl.href = config.logo_url;
@@ -47,6 +46,11 @@ export class App implements OnInit, OnDestroy {
   }
 
   ngOnInit(): void {
+    // Start watching router for automatic SEO metadata updates per route.
+    this.seoService.watchRouter();
+    // Handle the initial route (NavigationEnd already fired before ngOnInit).
+    this.seoService.resetToDefaults();
+
     // Defer until the navbar is rendered in the DOM.
     queueMicrotask(() => {
       this.navbarEl = document.querySelector('app-navbar');