- add chat_notification_settings table and migration
- add chat notifications API (get/update muted)
- skip message notifications for muted recipients
- add mute/unmute control in chat info panel
- add Saved Messages system chat with dedicated API
- add public group/channel metadata and discover/join endpoints
- add chat delete flow with for_all option and channel-wide delete
- switch message actions to context menu and improve reply/forward visuals
- improve microphone permission handling for voice recording
- add reply_to/forwarded_from message fields and chat pinned_message field
- add forward and pin APIs plus reply support in message create
- wire web actions: Reply, Fwd, Pin and reply composer state
- fix spam policy bug: allow repeated identical messages, keep rate limiting