Add persistent caller voices, Discord, REC/on-air linking, SEO fixes, ep9

- Returning callers now keep their voice across sessions (stored in regulars.json)
- Backfilled voice assignments for all 11 existing regulars
- Discord button on homepage + link in all page footers
- REC and On-Air buttons now toggle together (both directions)
- Fixed host mic double-stream bug (stem_mic vs host_stream conflict)
- SEO: JSON-LD structured data on episode + how-it-works pages
- SEO: noscript fallbacks, RSS links, twitter meta tags
- Episode 9 transcript and sitemap update

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

publish_episode.py

@@ -58,6 +58,7 @@ CASTOPOD_PASSWORD = "podcast2026api"
 PODCAST_ID = 1
 PODCAST_HANDLE = "LukeAtTheRoost"
 OPENROUTER_API_KEY = os.getenv("OPENROUTER_API_KEY")
+
 WHISPER_MODEL = "base"  # Options: tiny, base, small, medium, large
 
 # NAS Configuration for chapters upload
@@ -543,6 +544,7 @@ def add_episode_to_sitemap(slug: str):
     print(f"    Added episode to sitemap.xml")
 
 
+
 def get_next_episode_number() -> int:
     """Get the next episode number from Castopod."""
     headers = get_auth_header()