Harden CSRF/CSP and add hash version upgrades

Data/Migrations/20260218194640_AddPasswordHashVersion.cs

@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace GameList.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddPasswordHashVersion : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "PasswordHashVersion",
+                table: "Players",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 1);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "PasswordHashVersion",
+                table: "Players");
+        }
+    }
+}