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/ContextSummaryItem.cs

@@ -0,0 +1,10 @@
+namespace TaskTracker.Core.DTOs;
+
+public class ContextSummaryItem
+{
+    public string AppName { get; set; } = string.Empty;
+    public string Category { get; set; } = string.Empty;
+    public int EventCount { get; set; }
+    public DateTime FirstSeen { get; set; }
+    public DateTime LastSeen { get; set; }
+}