chore: initial commit of TaskTracker project

Existing ASP.NET API with vanilla JS SPA, WindowWatcher, Chrome extension, and MCP server.

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

TaskTracker.Core/DTOs/ApiResponse.cs

@@ -0,0 +1,20 @@
+namespace TaskTracker.Core.DTOs;
+
+public class ApiResponse<T>
+{
+    public bool Success { get; set; }
+    public T? Data { get; set; }
+    public string? Error { get; set; }
+
+    public static ApiResponse<T> Ok(T data) => new() { Success = true, Data = data };
+    public static ApiResponse<T> Fail(string error) => new() { Success = false, Error = error };
+}
+
+public class ApiResponse
+{
+    public bool Success { get; set; }
+    public string? Error { get; set; }
+
+    public static ApiResponse Ok() => new() { Success = true };
+    public static ApiResponse Fail(string error) => new() { Success = false, Error = error };
+}