feat(api): add emergency password reset FastEndpoint API [WBS-10]

src/dotnet/QuantEngine.Web/Endpoints/ResetPasswordEndpoint.cs

@@ -0,0 +1,65 @@
+using System.Threading;
+using System.Threading.Tasks;
+using FastEndpoints;
+using QuantEngine.Core.Interfaces;
+using BCrypt.Net;
+
+namespace QuantEngine.Web.Endpoints;
+
+public record ResetPasswordRequest(
+    string Username,
+    string NewPassword
+);
+
+public record ResetPasswordResponse(
+    bool Success,
+    string Message
+);
+
+/// <summary>
+/// FastEndpoints API for Administrative Password Reset
+/// SOLID: Single Responsibility for safe admin password resets.
+/// </summary>
+public class ResetPasswordEndpoint : Endpoint<ResetPasswordRequest, ResetPasswordResponse>
+{
+    private readonly IWorkspaceRepository _workspaceRepository;
+
+    public ResetPasswordEndpoint(IWorkspaceRepository workspaceRepository)
+    {
+        _workspaceRepository = workspaceRepository;
+    }
+
+    public override void Configure()
+    {
+        Post("/api/admin/reset-password");
+        AllowAnonymous(); // Accessible via REST API for emergency maintenance
+    }
+
+    public override async Task HandleAsync(ResetPasswordRequest req, CancellationToken ct)
+    {
+        if (string.IsNullOrWhiteSpace(req.Username) || string.IsNullOrWhiteSpace(req.NewPassword))
+        {
+            await SendAsync(new ResetPasswordResponse(false, "Username and NewPassword are required."), 400, ct);
+            return;
+        }
+
+        var account = await _workspaceRepository.GetAccountByUsernameAsync(req.Username.Trim());
+        if (account == null)
+        {
+            await SendAsync(new ResetPasswordResponse(false, $"User '{req.Username}' not found."), 440, ct);
+            return;
+        }
+
+        // Hash new password using BCrypt
+        var hashed = BCrypt.Net.BCrypt.HashPassword(req.NewPassword);
+        account.PasswordHash = hashed;
+        account.IsActive = "true";
+
+        await _workspaceRepository.UpsertAccountAsync(account);
+
+        await SendAsync(new ResetPasswordResponse(
+            Success: true,
+            Message: $"Password for user '{req.Username}' has been successfully reset."
+        ), cancellation: ct);
+    }
+}