- Add dedicated TitlesChannel (0xFFF9) following the VersionChannel pattern
- Server encodes name→title map via EncodeTitlesData/DecodeTitlesData
- Metadata wire format unchanged for backward compatibility with old clients
- All three fetchers (public Telegram, MTProto, X/Nitter) extract and store display names
- Client fetches TitlesChannel with a 10s deadline; falls back to channel handles gracefully on old servers
- Old clients are unaffected — they never query 0xFFF9