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/schedule/schedule.component.ts

@@ -1,10 +1,11 @@
-import { Component, inject } from '@angular/core';
+import { Component, effect, inject } from '@angular/core';
 import { AsyncPipe } from '@angular/common';
 import { map, Observable, startWith } from 'rxjs';
 
 import { ShowService } from '../services/show.service';
 import { Show } from '../interfaces/show';
 import { StationConfigService } from '../services/station-config.service';
+import { StructuredDataService } from '../services/structured-data.service';
 import { SortSchedulesPipe } from '../pipes/sort-schedules.pipe';
 import { resolveImageUrl } from '../services/app-config.service';
 
@@ -23,6 +24,7 @@ interface ScheduleState {
 export class ScheduleComponent {
   private showService = inject(ShowService);
   readonly config = inject(StationConfigService).config;
+  private structuredData = inject(StructuredDataService);
 
   /** ID of the currently expanded show card — null means none. */
   expandedShowId: number | null = null;
@@ -47,4 +49,14 @@ export class ScheduleComponent {
   resolveImageUrl(url: string): string {
     return resolveImageUrl(url);
   }
+
+  constructor() {
+    // Feed active shows to structured data for RadioSeason schema injection.
+    effect(() => {
+      const snapshot = this.showService.getShows();
+      snapshot.subscribe((shows) => {
+        this.structuredData.activeShows.set(shows);
+      });
+    });
+  }
 }