Store round start date in the database (#21153)

Content.Server.Database/Migrations/Postgres/20231021071411_RoundStartDate.cs

@@ -0,0 +1,39 @@
+#nullable disable
+
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+namespace Content.Server.Database.Migrations.Postgres
+{
+    /// <inheritdoc />
+    public partial class RoundStartDate : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<DateTime>(
+                name: "start_date",
+                table: "round",
+                type: "timestamp with time zone",
+                nullable: false,
+                defaultValue: new DateTime(1, 1, 1, 0, 0, 0, 0, DateTimeKind.Unspecified));
+
+            migrationBuilder.CreateIndex(
+                name: "IX_round_start_date",
+                table: "round",
+                column: "start_date");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_round_start_date",
+                table: "round");
+
+            migrationBuilder.DropColumn(
+                name: "start_date",
+                table: "round");
+        }
+    }
+}