Hope Support (Beta) + retro fallbacks!

HOPE encryption support - Implements the Hotline One-time Password Extension (HOPE) for secure authentication and optional RC4 transport encryption. Includes MAC algorithm negotiation (HMAC-SHA1, SHA1, HMAC-MD5, MD5, INVERSE), session key exchange, and per-bookmark HOPE toggle in the UI. Retro server compatibility fixes - Improves compatibility with 1990s/early 2000s Hotline servers: protocol version downgrade (v2 → v1 fallback), MacRoman string encoding, legacy news category parsing (field 320), non-FILP file transfer fallback, and a reconnect delay after HOPE probe failure to avoid IP bans. Version bump to 0.2.1