- chat_core: defer one-time-prekey deletion until the first message
decrypts successfully; deleting it on load made the SPK grace-period
retry derive a wrong shared secret and lose the message permanently
- chat_core: fix get_deleted_since params (since -> since_ts) and
response field (message_ids -> deleted_ids) so incremental deletion
sync actually works
- chat_core: route keys_updated pushes into the notification queue
- server: notify contacts with keys_updated when a user uploads a new
SPK or logs in with a new device, so clients invalidate cached key
bundles instead of waiting for the TTL
- server: rate-limit download_stream like other heavy handlers
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
