Add backend refinements, new API tests, and fix flaky tests

[tjementum]

Summary & Motivation

Add SharedKernel improvements, new API tests, and fix flaky tests caused by non-deterministic test data.

• Add StronglyTypedString<T> base class for creating string-based strongly typed IDs with optional prefix validation (Stripe-style IDs like cus_abc123).
• Add IBlobStorageClient interface to enable mocking and improve testability.
• Add Result.Redirect() and corresponding ApiResult support for HTTP redirects.
• Add bulk repository interfaces IBulkAddRepository<T> and IBulkUpdateRepository<T>, and rename BulkRemove to RemoveRange for consistency with EF Core naming.
• Add AddRangeAsync, UpdateRange, and RemoveRange methods to RepositoryBase.
• Add MapStronglyTypedString and OwnedNavigationBuilder overloads to ModelBuilderExtensions for EF Core mapping of owned entities.
• Add CreateContainerIfNotExistsAsync, DeleteIfExistsAsync, and User Delegation Key SAS support to BlobStorageClient.
• Fix UseStringForEnums to handle nullable enum properties.
• Simplify email validation by using MailAddress.TryCreate instead of custom regex rules.
• Move AddCrossServiceDataProtection from ApiDependencyConfiguration to SharedDependencyConfiguration.
• Exclude owned entities from global tenant query filters to fix query issues.
• Fix NotSupportedException when copying avatar during tenant switch by buffering Azure's non-seekable stream.
• Add API tests for Logout, ChangeLocale, and ChangeUserRole commands.
• Fix flaky tests by adding Faker.Internet.UniqueEmail() to prevent email collisions when tests run in parallel.
• Fix flaky test using Faker.Random.String2() instead of String() to avoid whitespace trimming issues.

Downstream projects

1. Update any BlobStorageClient usage to use the IBlobStorageClient interface:

- BlobStorageClient blobStorageClient
+ IBlobStorageClient blobStorageClient

- services.AddKeyedSingleton("your-self-contained-system-storage",
+ services.AddKeyedSingleton<IBlobStorageClient>("your-self-contained-system-storage",

2. Rename BulkRemove to RemoveRange in repositories:

- repository.BulkRemove(entities);
+ repository.RemoveRange(entities);

Checklist

• I have added tests, or done manual regression tests
• I have updated the documentation, if necessary

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
49.2% Coverage on New Code
1.3% Duplication on New Code

See analysis details on SonarQube Cloud