fix: real-time bg messages, join clears invite, richer seen-by, nicer badge (0.1.10/batch63)

1. Notifications/messages lagged when the desktop window was backgrounded —
   Electron throttles hidden renderers by default, stalling the chat WS's
   onmessage + timers. Set backgroundThrottling:false → real-time in the tray.
   (Transport is WebSocket; no Firebase needed.)
2. Joining a call via the header Join button left the Join/Decline invite popup
   on screen — enterMeeting now dismisses the invite (and stops the ring).
3. Seen-by is now "Message info": real contact DPs, a "Not seen yet" list for
   groups, and dark lettering (white-on-pastel initials were invisible).
4. App-icon unread badge: red→pink gradient pill with a white ring + shadow,
   drawn at 2x, instead of a flat red disc.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

desktop/package.json

@@ -1,6 +1,6 @@
 {
   "name": "biz-connect-desktop",
-  "version": "0.1.9",
+  "version": "0.1.10",
   "description": "Biz Connect technician desktop client — loads the Connect web UI with native screen capture",
   "author": {
     "name": "BizGaze",