Add BunnyCDN integration, on-air website badge, publish script fixes

- On-air toggle uploads status.json to BunnyCDN + purges cache, website
  polls it every 15s to show live ON AIR / OFF AIR badge
- Publish script downloads Castopod's copy of audio for CDN upload
  (byte-exact match), removes broken slug fallback, syncs all episode
  media to CDN after publishing
- Fix f-string syntax error in publish_episode.py (Python <3.12)
- Enable CORS on BunnyCDN pull zone for json files
- CDN URLs for website OG images, stem recorder bug fixes, LLM token
  budget tweaks, session context in CLAUDE.md

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

website/css/style.css

@@ -112,6 +112,75 @@ a:hover {
   margin-bottom: 0.25rem;
 }
 
+/* On-Air Badge */
+.on-air-badge {
+  display: none;
+  align-items: center;
+  justify-content: center;
+  gap: 0.5rem;
+  background: var(--accent-red);
+  color: #fff;
+  padding: 0.4rem 1.2rem;
+  border-radius: 50px;
+  font-size: 0.85rem;
+  font-weight: 800;
+  letter-spacing: 0.12em;
+  text-transform: uppercase;
+  animation: on-air-glow 2s ease-in-out infinite;
+  margin-bottom: 0.5rem;
+}
+
+.on-air-badge.visible {
+  display: inline-flex;
+}
+
+.on-air-dot {
+  width: 8px;
+  height: 8px;
+  border-radius: 50%;
+  background: #fff;
+  animation: on-air-blink 1s step-end infinite;
+}
+
+@keyframes on-air-glow {
+  0%, 100% { box-shadow: 0 0 8px rgba(204, 34, 34, 0.5); }
+  50% { box-shadow: 0 0 20px rgba(204, 34, 34, 0.8); }
+}
+
+@keyframes on-air-blink {
+  0%, 100% { opacity: 1; }
+  50% { opacity: 0.3; }
+}
+
+/* Off-Air Badge */
+.off-air-badge {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  background: #444;
+  color: var(--text-muted);
+  padding: 0.35rem 1.1rem;
+  border-radius: 50px;
+  font-size: 0.8rem;
+  font-weight: 700;
+  letter-spacing: 0.1em;
+  text-transform: uppercase;
+  margin-bottom: 0.5rem;
+}
+
+.off-air-badge.hidden {
+  display: none;
+}
+
+.phone.live .phone-number {
+  color: var(--accent-red);
+  text-shadow: 0 0 16px rgba(204, 34, 34, 0.35);
+}
+
+.phone.live .phone-label {
+  color: var(--text);
+}
+
 /* Subscribe buttons */
 .subscribe-row {
   display: flex;