desktop: electron-builder 26.16.1, which can sign on a macOS 26 runner

26.15.3 hands the .p12's password to `security set-key-partition-list -k`,
which wants the temporary keychain's own. macOS 26 checks it, so the first
signed build stopped there. Upstream fixed it in 26.16.0 (their #10172).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: Jing-yilin

desktop/bun.lock

@@ -14,7 +14,7 @@
   "devDependencies": {
     "@types/node": "26",
     "electron": "44.4.3",
-    "electron-builder": "26.15.3",
+    "electron-builder": "26.16.1",
     "typescript": "7"
   },
   "trustedDependencies": [