feat: add EstimatedMinutes field and general PUT update endpoint for tasks

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

TaskTracker.Infrastructure/Migrations/20260227031015_AddEstimatedMinutes.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace TaskTracker.Infrastructure.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddEstimatedMinutes : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "EstimatedMinutes",
+                table: "Tasks",
+                type: "int",
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "EstimatedMinutes",
+                table: "Tasks");
+        }
+    }
+}