chore(identity): add migration for email field and email_codes table

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/identity-service/prisma/migrations/20241224000000_add_email_field/migration.sql

@@ -0,0 +1,27 @@
+-- AlterTable
+ALTER TABLE "user_accounts" ADD COLUMN "email" VARCHAR(100);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "user_accounts_email_key" ON "user_accounts"("email");
+
+-- CreateIndex
+CREATE INDEX "idx_email" ON "user_accounts"("email");
+
+-- CreateTable
+CREATE TABLE "email_codes" (
+    "id" BIGSERIAL NOT NULL,
+    "email" VARCHAR(100) NOT NULL,
+    "code" VARCHAR(10) NOT NULL,
+    "purpose" VARCHAR(50) NOT NULL,
+    "expires_at" TIMESTAMP(3) NOT NULL,
+    "created_at" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "used_at" TIMESTAMP(3),
+
+    CONSTRAINT "email_codes_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "idx_email_purpose" ON "email_codes"("email", "purpose");
+
+-- CreateIndex
+CREATE INDEX "idx_email_expires" ON "email_codes"("expires_at");