[ci skip] f1-stream: add CDN token refresh, SvelteKit frontend, multi-stream layout (Phases 6-8)

- Phase 6: CDN token lifecycle with 3-strategy URL matching and periodic refresh
- Phase 7: SvelteKit 2/Svelte 5 frontend with schedule calendar and hls.js player
- Phase 8: Multi-stream layout supporting up to 4 simultaneous HLS streams
- Update Dockerfile to multi-stage build (Node.js frontend + Python backend)
- Switch deployment to :latest tag with Always pull policy for CI-driven deploys
- Update Woodpecker CI to use explicit latest tag

stacks/f1-stream/files/frontend/src/lib/stores.js

@@ -0,0 +1,13 @@
+import { writable } from 'svelte/store';
+
+/** Schedule data store */
+export const schedule = writable(null);
+
+/** Streams data store */
+export const streams = writable(null);
+
+/** Loading state */
+export const loading = writable(false);
+
+/** Error state */
+export const error = writable(null);