Port PR 65532: fix Blazor template EF migration baseline

[Copilot]

Port PR 65532: fix Blazor template EF migration baseline

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Summary of the changes (Less than 80 chars)

Port PR 65532: align Blazor template app.db migration baseline

Description

This ports the effective changes from #65532 to main to fix the Blazor Web App (Individual auth + SQLite) migration baseline mismatch that causes dotnet ef database update to fail against the shipped template database.

• Template DB migration baseline

  • Updated the shipped Blazor template app.db so __EFMigrationsHistory records 00000000000000_CreateIdentitySchema instead of a timestamped migration ID.

• Regression coverage in template tests

  • Extended BlazorTemplateTest for the Individual-auth SQLite path to run EF update + add migration and assert no schema diff.

if (args.Contains(ArgConstants.IndividualAuth) && !args.Contains(ArgConstants.UseLocalDb))
{
    await project.RunDotNetEfUpdateDatabaseAsync();
    await project.RunDotNetEfCreateMigrationAsync("blazor");
    project.AssertEmptyMigration("blazor");
}

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[dotnet-policy-service]

Hey @dotnet/aspnet-build, looks like this PR is something you want to take a look at.