Improve recovery flows and external navigation

[jamesmontemagno]

Summary

• add recoverable Local Vault unlock flows across Apple, Google, keystore, push, settings, and CI wizard experiences
• make Settings show the current version and launch the existing upgrade flow when an update is available
• open external links through the native browser and make Xcode sign-in submit with Enter
• expand the Blazor error bar with captured diagnostics and a prefilled upstream issue action

Code review

Reviewed the complete diff for initialization races, event cleanup, internal versus external navigation, duplicate recovery UI, first-access vault failures, and Razor submission behavior. The identified issues were fixed before this PR.

Validation

• dotnet build src/MauiSherpa/MauiSherpa.csproj -f net10.0-maccatalyst --verbosity minimal
• dotnet test tests/MauiSherpa.Core.Tests/MauiSherpa.Core.Tests.csproj --filter "FullyQualifiedName~UpdateServiceTests" --verbosity minimal (17 passed)
• node --check src/MauiSherpa/wwwroot/js/errorInterop.js
• git diff --check