[Feature] Use navigator.install() for PWA installation with a fallback

[chdenat]

Context

Studio currently uses its existing JavaScript-based PWA installation flow. The Web Install API should become the primary installation entry point when the browser exposes navigator.install().

Requested behavior

• Use navigator.install() from the Web Awesome Install button when supported.
• Keep the call directly behind the user activation supplied by the Install button.
• Detect when the Web Install API is unavailable or cannot install Studio.
• Fall back to the existing beforeinstallprompt installation flow in those cases.
• Open the existing browser-specific manual instructions when no native prompt is available.
• Keep the existing dismiss and settings entry points.

Acceptance criteria

• Supported browsers call navigator.install() when the user selects Install.
• Browsers without the Web Install API use the current native installation prompt when available.
• Browsers where installation is unavailable use the existing manual fallback instructions.
• A rejected Web Install API call does not leave an unusable installation dialog open.
• The Install action uses the Web Awesome button and the Font Awesome desktop-arrow-down icon.
• Automated tests cover the Web Install API, the existing prompt fallback, and the manual fallback.

Technical notes

The primary integration belongs in src/components/AppUpdate.jsx.

The existing fallback is implemented through the current PWA installation flow in:

• src/core/ui/AppUpdateManager.js
• src/components/AppUpdate.jsx
• src/components/Settings/application/style/PWASettings.jsx

The implementation must use feature detection because the Web Install API is not available in every browser.