Add LINE Messaging API as the 9th messaging channel using HTTP Webhook.
Supports text/image/audio messages, group chat @mention detection,
reply with quote, and loading animation.
- No external SDK required (standard library only)
- HMAC-SHA256 webhook signature verification
- Reply Token (free) with Push API fallback
- Group chat: respond only when @mentioned
- Quote original message in replies using quoteToken
Closes#146
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
f294a71bc5