- 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
- add owner/admin/member permission checks
- implement member add/remove, role updates, and leave flow
- add chat title update endpoint for manageable chat types
