feat: add delete button to exports list and detail pages

Add DELETE /api/exports/{id} endpoint with cascade delete, trash icon
buttons on both the exports list and export detail pages, and disable
browser caching for static files to prevent stale JS issues.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

FabWorks.Api/Program.cs

@@ -17,6 +17,10 @@ builder.Services.AddScoped<IFileStorageService, FileStorageService>();
 var app = builder.Build();
 
 app.UseDefaultFiles();
-app.UseStaticFiles();
+app.UseStaticFiles(new StaticFileOptions
+{
+    OnPrepareResponse = ctx =>
+        ctx.Context.Response.Headers.Append("Cache-Control", "no-cache, no-store")
+});
 app.MapControllers();
 app.Run();