[release/10.0-preview7] Passkey design follow-ups

[MackinnonBuck]

Backport of #62530

Passkey design follow-ups

Addresses API review feedback for passkey support

Description

This PR implements follow-up changes from the API review of passkey support in ASP.NET Core Identity (#62287). This also includes updates to the Blazor Web App project template to make use of the updated APIs. The changes ensure the passkey APIs meet the quality bar for the release and incorporate design improvements identified during review.

Fixes #62287

Customer Impact

These changes improve the usability of the new passkey authentication feature in ASP.NET Core Identity. While this PR contains breaking API changes, the APIs being changed were only introduced in .NET 10 preview 6, so we don't expect customer apps to be heavily relying on them.

Regression?

• Yes
• No

This is a new feature being introduced, not a bug fix to existing functionality.

Risk

• High
• Medium
• Low

While this PR includes breaking changes to the passkey APIs, the initial revision was released in preview 6. Therefore, direct customer usage of these preview APIs is expected to be minimal. The changes in this PR only apply to passkey functionality and are unlikely to impact other parts of the product.

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

[Copilot]

Pull Request Overview

This PR implements follow-up changes from the API review of passkey support in ASP.NET Core Identity, simplifying the passkey APIs and improving their design based on review feedback.

• Streamlined passkey API by removing intermediate options classes and simplifying method signatures
• Refactored passkey data storage to use a single IdentityPasskeyData class with JSON serialization
• Updated all template and sample code to use the new simplified APIs

Reviewed Changes

Copilot reviewed 73 out of 76 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
Database schema files	Updated Entity Framework model snapshots and migrations to use JSON storage for passkey data
PasskeySubmit.razor	Added antiforgery token support for secure passkey operations
Identity template files	Updated Blazor templates to use simplified AddOrUpdatePasskeyAsync and streamlined passkey methods
Core passkey classes	Replaced complex options pattern with simpler PasskeyHandler and direct JSON result methods
Test files	Updated all tests to match the new simplified API surface
Store implementations	Modified to use new AddOrUpdatePasskeyAsync method and JSON-based passkey data storage

Files not reviewed (2)

• src/ProjectTemplates/Web.ProjectTemplates/content/BlazorWeb-CSharp/BlazorWebCSharp.1/Data/SqlLite/00000000000000_CreateIdentitySchema.Designer.cs: Language not supported
• src/ProjectTemplates/Web.ProjectTemplates/content/BlazorWeb-CSharp/BlazorWebCSharp.1/Data/SqlServer/00000000000000_CreateIdentitySchema.Designer.cs: Language not supported

[dotnet-policy-service]

Hi @@MackinnonBuck. This PR was just approved to be included in the upcoming servicing release. Somebody from the @dotnet/aspnet-build team will get it merged when the branches are open. Until then, please make sure all the CI checks pass and the PR is reviewed.