Refactor Login page to use MediatR commands/queries

[Copilot]

The Login IndexModel had SignInManager<ApplicationUser> injected directly into the page model constructor. This refactors it to dispatch through MediatR, consistent with the rest of the application.

Changes

• ExternalProviderDetails model added to SecurityService.Models for use across the business logic layer
• GetExternalProvidersQuery added to SecurityServiceQueries — retrieves external auth schemes sorted by display name
• LoginCommand added to SecurityServiceCommands — takes Username, Password, RememberLogin
• LoginRequestHandler (new) — handles both the query and command via SignInManager; distinguishes IsLockedOut, IsNotAllowed, and RequiresTwoFactor states with specific error messages rather than a generic failure
• Login/Index.cshtml.cs — constructor now takes only IMediator; failure messages from the handler are surfaced directly to ModelState
• LoginPageModelTests — updated to mock IMediator instead of SignInManager

// Before
public IndexModel(SignInManager<ApplicationUser> signInManager) { ... }

// After
public IndexModel(IMediator mediator) { ... }

// Handler dispatched on POST
var result = await this._mediator.Send(
    new SecurityServiceCommands.LoginCommand(Input.Username, Input.Password, Input.RememberLogin));

The handler is auto-discovered via the existing RegisterServicesFromAssembly(typeof(SecurityServiceCommands).Assembly) in Program.cs — no DI wiring changes required.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• f.feedz.io
  • Triggering command: /usr/bin/dotnet dotnet build SecurityService.slnx --configuration Release (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore SecurityService.UnitTests/SecurityService.UnitTests.csproj (dns block)
  • Triggering command: /opt/hostedtoolcache/CodeQL/2.25.1/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp /opt/hostedtoolcache/CodeQL/2.25.1/x64/codeql/csharp/tools/linux64/Semmle.Autobuild.CSharp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 8 complexity · -1 duplication

Metric	Results
Complexity	8
Duplication	-1

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