The live-message push now carries both parties, so an incoming message opens
that conversation's dock window if it's closed, or flashes it once if it's
already open (expanded or minimised, without disturbing the minimised state) —
only for messages from someone else, never your own echo.
Dock state (open windows + minimised state) is persisted per user, so a reload
restores exactly what was open, minimised, or closed.
Move messaging out of the notification center into its own left-nav module
(own page, own unread badge), so a reload returns to it and notifications stay
separate. Add a Messenger-style floating dock (bottom-right): pop a conversation
out from the page, keep chatting across navigation, minimise (rollup) or close.
- Messages is now a routed page; NotificationsPanel reverts to inbox-only and the
nav badge no longer mixes in messages.
- Extract shared KeyGate + ChatThread (used by both the page and dock windows);
e2ee exposes a shared unlock subscription so page and dock agree.
- ChatDock (always mounted for human users) owns the app-wide live-message
subscription and per-device key restore. EN/HU/DE strings.
