Replace Spotify embeds with branded custom audio player backed by RSS

- Add /api/episode-audio route returning MP3 URLs from Anchor RSS feed
- Replace Spotify URL text inputs in admin with RSS episode dropdowns
- New EpisodeAudioPlayer component with podcast art, show name, progress
  bar, and Spotify icon link — full and compact sizes
- Backward-compatible: legacy Spotify embed URLs still render as iframes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/App.tsx

@@ -11,6 +11,7 @@ import { DEFAULTS } from './content'
 import { usePageMeta } from './hooks/usePageMeta'
 import { useGlobalSearch } from './hooks/useGlobalSearch'
 import { GlobalSearch } from './components/GlobalSearch'
+import { EpisodeAudioPlayer } from './components/EpisodeAudioPlayer'
 import './App.css'
 
 const SPOTIFY_EMBED_URL =
@@ -1564,15 +1565,19 @@ function EpisodeDetailPage({ content }: { content: SiteContent }) {
 
           {resolvedEmbedUrl && (
             <div className="episode-detail-embed">
-              <iframe
-                src={resolvedEmbedUrl}
-                title={episode.title}
-                width="100%"
-                height="152"
-                frameBorder="0"
-                allow="autoplay; clipboard-write; encrypted-media; fullscreen; picture-in-picture"
-                loading="lazy"
-              />
+              {resolvedEmbedUrl.includes('spotify.com') ? (
+                <iframe
+                  src={resolvedEmbedUrl}
+                  title={episode.title}
+                  width="100%"
+                  height="152"
+                  frameBorder="0"
+                  allow="autoplay; clipboard-write; encrypted-media; fullscreen; picture-in-picture"
+                  loading="lazy"
+                />
+              ) : (
+                <EpisodeAudioPlayer src={resolvedEmbedUrl} title={episode.title} size="full" spotifyUrl={episode.url || content.platformSpotifyUrl} />
+              )}
             </div>
           )}