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).
