feat(backend): add admin evaluation history, engine, simulation, bot API controllers and global exception middleware

FinlyticBackend/Middleware/GlobalExceptionHandler.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Diagnostics;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+
+namespace FinlyticBackend.Middleware;
+
+/// <summary>
+/// Global fallback exception handler for the Gateway (Rules.md §11). Converts any unhandled exception that
+/// escapes a controller action, hub method, or other endpoint into a standardized RFC 7807 Problem Details
+/// response instead of an ad-hoc anonymous error object or a leaked stack trace.
+/// Registered via <c>AddExceptionHandler&lt;GlobalExceptionHandler&gt;()</c> and activated by
+/// <c>app.UseExceptionHandler()</c> in <c>Program.cs</c>. This only intercepts exceptions thrown while a
+/// request is being handled; it has no effect on the fail-fast startup checks in <c>Program.cs</c>
+/// (missing/weak <c>JWT:SecretKey</c>, missing <c>ADMIN:DefaultPassword</c>), which throw before
+/// <c>builder.Build()</c> - i.e. before this middleware pipeline exists - and are intentionally left
+/// unhandled so the host refuses to start.
+/// </summary>
+public sealed class GlobalExceptionHandler : IExceptionHandler
+{
+    private readonly ILogger<GlobalExceptionHandler> _logger;
+
+    public GlobalExceptionHandler(ILogger<GlobalExceptionHandler> logger)
+    {
+        _logger = logger;
+    }
+
+    /// <inheritdoc />
+    public async ValueTask<bool> TryHandleAsync(HttpContext httpContext, Exception exception, CancellationToken cancellationToken)
+    {
+        _logger.LogError(
+            exception,
+            "Unhandled exception while processing {Method} {Path}",
+            httpContext.Request.Method,
+            httpContext.Request.Path);
+
+        httpContext.Response.StatusCode = StatusCodes.Status500InternalServerError;
+
+        var problemDetailsService = httpContext.RequestServices.GetRequiredService<IProblemDetailsService>();
+        return await problemDetailsService.TryWriteAsync(new ProblemDetailsContext
+        {
+            HttpContext = httpContext,
+            Exception = exception,
+            ProblemDetails = new ProblemDetails
+            {
+                Status = StatusCodes.Status500InternalServerError,
+                Title = "An unexpected error occurred.",
+                Detail = "The Gateway encountered an unexpected error while processing the request.",
+                Type = "https://tools.ietf.org/html/rfc7231#section-6.6.1"
+            }
+        });
+    }
+}