fix(web): address code review findings from Razor Pages migration

- Remove legacy wwwroot files (old index.html, app.css, api.js, page scripts)
- Add Index page that redirects / to /board
- Fix mapping delete button missing handler=Delete in URL
- Add [IgnoreAntiforgeryToken] to AnalyticsModel for consistency
- Remove duplicate JS from _TaskDetail.cshtml (already in app.js)

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

TaskTracker.Api/Pages/Analytics.cshtml.cs

@@ -7,6 +7,7 @@ using TaskTracker.Core.Interfaces;
 
 namespace TaskTracker.Api.Pages;
 
+[IgnoreAntiforgeryToken]
 public class AnalyticsModel : PageModel
 {
     private readonly ITaskRepository _taskRepo;