Make Avalonia Browser usable on small screens with zoom and panning

[highbyte]

The Avalonia Browser app previously clipped its desktop layout on small screens, making emulator controls and enlarged displays difficult to reach. This change fits the complete canvas to the available window and provides zoom, Reset, scrolling, and touch panning while keeping the toolbar at a stable size on iPhone.

• Measure the Avalonia content dynamically so larger emulator Scale settings remain reachable; hide the collapsible toolbar when the unscaled app fits.
• Center overlays, including nested acknowledgments, within the visible canvas area and route scrolling into an open overlay.
• Offer manual orientation switching where supported, with dismissible guidance when the browser cannot lock orientation.
• Fix Safari Download & Run by leaving browser User-Agent selection to the browser, guard zero-duration timing measurements, and revise the Safari compatibility notice.
• Run browser behavior checks in independent CI and Sonar, import JavaScript coverage, and verify manual Sonar analyses against the requested branch and commit.

Validation: Browser Debug build passed without warnings; browser behavior and instrumentation checks passed; branch build/test, Sonar analysis, and beta publishing workflows passed. The published beta's zoom controls were manually verified by the user in Brave on iPhone. Automated browser checks model the DOM and browser APIs; physical orientation locking and older Safari compatibility remain device-dependent.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
96.9% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud