feat(frontend): Vue 3 wizard UI (nostr login, episode upload, go-live)

- NIP-07 login → NIP-98 signed request → session cookie
- episode wizard: pick/create podcast (incl. lightning address question),
  browser-side sha256 + BUD-02 blossom upload with progress, feed result page
- live wizard + stream dashboard: OBS server/key (shown once, rotatable),
  browser WHIP publishing (camera or screen), hls.js live preview,
  publish-recording-as-episode flow
- settings view: external blossom URL, relay list, public URL (admin only)

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/main.ts

@@ -0,0 +1,7 @@
+import { createApp } from 'vue';
+import { createPinia } from 'pinia';
+import App from './App.vue';
+import { router } from './router';
+import './style.css';
+
+createApp(App).use(createPinia()).use(router).mount('#app');