Avoid Firefox/macOS WebGPU shader failure by falling back to WebGL

[Copilot]

Firefox 146 on macOS can fail WebGPU pipeline compilation (Metal ... redefinition of '_tmp'), leaving the 3D canvas white. This change avoids that browser/OS-specific failure by selecting a safe rendering backend at engine init time.

• Engine selection hardening

  • Added shouldUseWebGPUEngine(userAgent, platform) in babylon-jsview.directive.ts.
  • initEngine now uses:
    • WebGPU for all existing supported environments.
    • WebGL (Engine) specifically for Firefox on macOS.
  • Updated engine typing to support all runtime engine variants used by this directive (WebGPUEngine | Engine | NullEngine).

• Targeted compatibility coverage

  • Extended babylon-jsview.directive.spec.ts with explicit assertions for:
    • Firefox + macOS → WebGPU disabled.
    • Firefox + non-macOS → WebGPU remains enabled.

export function shouldUseWebGPUEngine(userAgent: string, platform: string): boolean {
  const isFirefox = /firefox/i.test(userAgent);
  const isMac = /mac/i.test(platform);
  return !(isFirefox && isMac);
}

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• fonts.googleapis.com
  • Triggering command: /home/REDACTED/.cache/ms-playwright/chromium_headless_shell-1217/chrome-headless-shell-linux64/chrome-headless-shell /home/REDACTED/.cache/ms-playwright/chromium_headless_shell-1217/chrome-headless-shell-linux64/chrome-headless-shell --disable-field-trial-config --disable-REDACTED-networking --disable-REDACTED-timer-throttling --disable-REDACTEDing-occluded-windows --disable-back-forward-cache --disable-breakpad --disable-client-side-phishing-detection --disable-component-extensions-with-REDACTED-pages --disable-component-update --no-default-browser-check --disable-default-apps --disable-dev-shm-usage --disable-extensions --disable-features=AvoidUnnecessaryBeforeUnloadCheckSync,BoundaryEventDispatchTracksNodeRemoval,DestroyProfileOnBrowserClose,DialMediaRouteProvider,GlobalMediaControls,HttpsUpgrades,LensOverlay,MediaRouter,PaintHolding,ThirdPartyStoragePartitioning,Transl -main/dist/ripgrep/bin/linux-x64/rg (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)