adding tests and docs for custom templates

EmailCollector.Api/Migrations/20241212054047_AddCustomEmailTemplates.cs

@@ -0,0 +1,51 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace EmailCollector.Api.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddCustomEmailTemplates : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "CustomEmailTemplates",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "TEXT", nullable: false),
+                    FormId = table.Column<Guid>(type: "TEXT", nullable: false),
+                    Event = table.Column<string>(type: "TEXT", nullable: false),
+                    TemplateSubject = table.Column<string>(type: "TEXT", nullable: false),
+                    TemplateBodyUri = table.Column<string>(type: "TEXT", nullable: false),
+                    IsActive = table.Column<bool>(type: "INTEGER", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "TEXT", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "TEXT", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_CustomEmailTemplates", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_CustomEmailTemplates_SignupForms_FormId",
+                        column: x => x.FormId,
+                        principalTable: "SignupForms",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_CustomEmailTemplates_FormId",
+                table: "CustomEmailTemplates",
+                column: "FormId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "CustomEmailTemplates");
+        }
+    }
+}