App: integrate reviewed workflow improvements and engine 1.1.6 #1450

Review and integrate the supplied app-improvements candidate on current main, retain the released beta.10 security and benchmark changes from #1255, and update the bundled macOS engine to the immutable 1.1.6 release.

Check the candidate against the current app, address verified review blockers, and rebuild with focused before/after regressions, the full app verification suite and isolated macOS packaged checks. Record remaining native or account-specific checks honestly. This work does not publish a new desktop release.