Improve PWA internal/external URL routing controls

[djangonavarro220]

Summary

This PR improves how PWAs decide whether a URL should stay inside the app window or open in the regular browser.

What changed

• infer in-app scope automatically from the app manifest / start URL when possible
• open out-of-scope links in the regular browser by default
• intercept external links earlier in the native browser hooks so direct external links are less likely to get absorbed by the PWA window
• add a per-app setting for explicit internal URL patterns
• support exact prefixes and wildcard patterns such as:
  • https://mail.google.com/mail/
  • https://*.google.com/*
  • https://domain.com/path/*
• prefill the install form start URL with the current app URL

Why

There are several long-running reports around:

• _blank / new-window links staying inside the PWA
• needing path-level or wildcard control instead of domain-only matching
• cases where a site mixes internal app routes with external links under related domains

This PR aims to improve the common case without requiring manual configuration for every app, while still allowing finer per-app control when needed.

Related to:

• Option to open target="_blank" links in the default browser #354
• Allow customizing app scope #411
• Suppport treating only a subset of a domain as internal #796
• Full URL exceptions for openOutOfScopeInDefaultBrowser #383

Notes

• tested locally with a custom build flow on macOS
• this is intentionally focused on routing behavior and small UI support for tuning it
• there may still be edge cases around complex SSO / redirect flows that need follow-up

[filips123]

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