fix(desktop 0.1.6): fast + persistent native notifications + screen picker

- Desktop notifications were slow (~15s), vanished in ~1s, and clicks did nothing:
  * don't block the toast on the avatar download (race a 600ms cap) → shows instantly
  * keep a strong reference to each Notification (Electron GC'd them → premature close
    + dead click)
  * call invites use timeoutType:'never' + a 45s window so they stay until clicked/ended;
    web marks call notifications persistent.
- #9: enable the OS screen/window PICKER (useSystemPicker) so users choose what to share
  (a single window avoids the whole-screen mirror); falls back to primary display.
- desktop 0.1.5 -> 0.1.6.

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

desktop/main.js

@@ -75,28 +75,47 @@ function avatarToTempPng(src) {
   });
 }
 
+// Keep STRONG references to live notifications. Electron/Windows garbage-collects a Notification
+// with no reference, which closed the toast within ~1s and made clicks do nothing.
+const activeNotifs = new Set();
+
 // Resolves {open} when the toast is clicked (renderer then opens that chat), else null.
 ipcMain.handle('reply-notification', async (_e, payload = {}) => {
   if (!Notification.isSupported()) return null;
-  const img = await avatarToTempPng(payload.avatar);
+  // Do NOT block the toast on the avatar download (that made desktop notifications lag ~15s vs the
+  // browser's instant one). Race it against a short cap: use the DP only if it's ready fast.
+  const img = await Promise.race([
+    avatarToTempPng(payload.avatar),
+    new Promise((r) => setTimeout(() => r(null), 600)),
+  ]);
   return await new Promise((resolve) => {
-  let done = false;
-  const finish = (v) => { if (!done) { done = true; if (img) { try { fs.unlinkSync(img); } catch (_) {} } resolve(v); } };
-  try {
-    const n = new Notification({
-      title: payload.title || 'Biz Connect',
-      body: payload.body || '',
-      icon: img ? nativeImage.createFromPath(img) : undefined,
-      silent: false,
-    });
-    n.on('click', () => {
-      if (win) { if (win.isMinimized()) win.restore(); win.show(); win.focus(); } // raise the app
-      finish({ kind: payload.kind, id: payload.id, open: true });
-    });
-    n.on('close', () => finish(null));
-    n.show();
-    setTimeout(() => finish(null), 30000); // don't leave the promise pending forever
-  } catch (_) { finish(null); }
+    let done = false;
+    let n;
+    const finish = (v) => {
+      if (done) return; done = true;
+      if (n) { activeNotifs.delete(n); }
+      if (img) { try { fs.unlinkSync(img); } catch (_) {} }
+      resolve(v);
+    };
+    try {
+      n = new Notification({
+        title: payload.title || 'Biz Connect',
+        body: payload.body || '',
+        icon: img ? nativeImage.createFromPath(img) : undefined,
+        silent: false,
+        // A call invite stays on screen until clicked/ended; a chat toast uses the default timeout.
+        timeoutType: payload.persistent ? 'never' : 'default',
+      });
+      activeNotifs.add(n); // strong ref → toast isn't collected; click stays live
+      n.on('click', () => {
+        if (win) { if (win.isMinimized()) win.restore(); win.show(); win.focus(); } // raise the app
+        finish({ kind: payload.kind, id: payload.id, open: true });
+      });
+      n.on('close', () => finish(null)); // user/system dismissed it → no action (don't force-close)
+      n.show();
+      // Safety timeout so the promise never leaks. Calls get the full ring window; chats shorter.
+      setTimeout(() => { try { if (n) n.close(); } catch (_) {} finish(null); }, payload.persistent ? 45000 : 25000);
+    } catch (_) { finish(null); }
   });
 });
 
@@ -195,13 +214,14 @@ const GRANTED = new Set([
 
 function configureSession() {
   const ses = session.fromPartition('persist:bizconnect');
-  // getDisplayMedia needs an explicit source. Default to the primary display + loopback audio.
-  // A production build can swap this for a source-picker window.
+  // getDisplayMedia: prefer the OS's native screen/window PICKER (Windows 11 / macOS) so the user
+  // chooses what to share (and can pick a single window, avoiding the whole-screen mirror). If the
+  // system picker isn't available, this handler falls back to auto-selecting the primary display.
   ses.setDisplayMediaRequestHandler((request, callback) => {
     desktopCapturer.getSources({ types: ['screen', 'window'] }).then((sources) => {
       callback(sources.length ? { video: sources[0], audio: 'loopback' } : {});
     }).catch(() => callback({}));
-  }, { useSystemPicker: false });
+  }, { useSystemPicker: true });
   // Async grant (getUserMedia, notifications, …)
   ses.setPermissionRequestHandler((_wc, permission, callback) => callback(GRANTED.has(permission)));
   // Sync check (some getUserMedia paths query this before requesting)