[ arbadacarbaYK/gittr ] CRITICAL: Add pubkey validation to ensure 64-char hex format
- Validate pubkey is 64-char hex at start of push process
- Log pubkey format for debugging
- Prevents using wrong pubkey format (npub, shortened, etc.)
- User's pubkey: 9a83779e75080556c656d4d418d02a4d7edbe288a2f9e6dd2b48799ec935184c