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.css

@@ -2702,6 +2702,178 @@
   margin: 0 0 2.5rem;
 }
 
+/* Custom audio player */
+.episode-audio-player {
+  background: var(--brand-black-2, #0f0f0c);
+  border: 1px solid rgba(201, 168, 76, 0.2);
+  border-radius: 10px;
+  padding: 1rem 1.1rem;
+}
+
+.episode-audio-player__inner {
+  display: flex;
+  align-items: center;
+  gap: 14px;
+}
+
+.episode-audio-player__art {
+  width: 56px;
+  height: 56px;
+  border-radius: 6px;
+  object-fit: cover;
+  flex-shrink: 0;
+}
+
+.episode-audio-player__body {
+  flex: 1;
+  min-width: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
+.episode-audio-player__meta {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+}
+
+.episode-audio-player__show-name {
+  font-size: 0.7rem;
+  color: var(--brand-gold, #c9a84c);
+  font-family: var(--brand-font-body, Georgia, serif);
+  letter-spacing: 0.02em;
+}
+
+.episode-audio-player__spotify-link {
+  color: rgba(176, 164, 140, 0.5);
+  display: flex;
+  align-items: center;
+  transition: color 0.15s;
+  flex-shrink: 0;
+}
+
+.episode-audio-player__spotify-link:hover {
+  color: #1DB954;
+}
+
+.episode-audio-player__spotify-link svg {
+  width: 16px;
+  height: 16px;
+}
+
+.episode-audio-player__title {
+  font-size: 0.88rem;
+  color: var(--brand-warm-white, #f0ead8);
+  margin: 0;
+  font-family: var(--brand-font-heading, Georgia, serif);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.episode-audio-player__controls {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  margin-top: 2px;
+}
+
+.episode-audio-player__play {
+  width: 34px;
+  height: 34px;
+  border-radius: 50%;
+  background: var(--brand-gold, #c9a84c);
+  border: none;
+  cursor: pointer;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  flex-shrink: 0;
+  color: var(--brand-black, #0a0a08);
+  transition: background 0.15s;
+}
+
+.episode-audio-player__play:hover {
+  background: var(--brand-gold-light, #e0c070);
+}
+
+.episode-audio-player__play svg {
+  width: 14px;
+  height: 14px;
+}
+
+.episode-audio-player__track {
+  flex: 1;
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  min-width: 0;
+}
+
+.episode-audio-player__bar {
+  position: relative;
+  height: 3px;
+  background: rgba(42, 37, 24, 0.9);
+  border-radius: 2px;
+  cursor: pointer;
+  outline: none;
+}
+
+.episode-audio-player__bar:focus-visible {
+  box-shadow: 0 0 0 2px var(--brand-gold, #c9a84c);
+}
+
+.episode-audio-player__fill {
+  height: 100%;
+  background: var(--brand-gold, #c9a84c);
+  border-radius: 2px;
+  pointer-events: none;
+}
+
+.episode-audio-player__thumb {
+  position: absolute;
+  top: 50%;
+  transform: translate(-50%, -50%);
+  width: 10px;
+  height: 10px;
+  border-radius: 50%;
+  background: var(--brand-gold-light, #e0c070);
+  pointer-events: none;
+}
+
+.episode-audio-player__times {
+  display: flex;
+  justify-content: space-between;
+  font-size: 0.68rem;
+  color: var(--brand-muted, #b0a48c);
+  font-family: var(--brand-font-body, Georgia, serif);
+}
+
+/* Compact variant (study sections) */
+.episode-audio-player--compact .episode-audio-player__art {
+  width: 42px;
+  height: 42px;
+}
+
+.episode-audio-player--compact .episode-audio-player__play {
+  width: 28px;
+  height: 28px;
+}
+
+.episode-audio-player--compact .episode-audio-player__play svg {
+  width: 11px;
+  height: 11px;
+}
+
+.episode-audio-player--compact .episode-audio-player__bar {
+  height: 2px;
+}
+
+.episode-audio-player--compact .episode-audio-player__title {
+  font-size: 0.8rem;
+}
+
 .episode-detail-show-notes,
 .episode-detail-questions {
   margin-top: 2.5rem;