feat: add domain-based access control for API keys (#198)

Co-authored-by: Claude <[email protected]>

apps/web/prisma/migrations/20250822125136_add_domain_access_to_api_keys/migration.sql

@@ -0,0 +1,5 @@
+-- AlterTable
+ALTER TABLE "ApiKey" ADD COLUMN     "domainId" INTEGER;
+
+-- AddForeignKey
+ALTER TABLE "ApiKey" ADD CONSTRAINT "ApiKey_domainId_fkey" FOREIGN KEY ("domainId") REFERENCES "Domain"("id") ON DELETE SET NULL ON UPDATE CASCADE;