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.Infrastructure/Migrations/20260227013459_AddSubTasks.cs

@@ -0,0 +1,49 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace TaskTracker.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddSubTasks : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "ParentTaskId",
+                table: "Tasks",
+                type: "int",
+                nullable: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Tasks_ParentTaskId",
+                table: "Tasks",
+                column: "ParentTaskId");
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_Tasks_Tasks_ParentTaskId",
+                table: "Tasks",
+                column: "ParentTaskId",
+                principalTable: "Tasks",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Restrict);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_Tasks_Tasks_ParentTaskId",
+                table: "Tasks");
+
+            migrationBuilder.DropIndex(
+                name: "IX_Tasks_ParentTaskId",
+                table: "Tasks");
+
+            migrationBuilder.DropColumn(
+                name: "ParentTaskId",
+                table: "Tasks");
+        }
+    }
+}