fix: removed userId from contact endpoint response (#6175)

Co-authored-by: Piyush Gupta <piyushguptaa2z123@gmail.com>

packages/database/migration/20250708044701_remove_userid_from_contact/migration.sql

@@ -0,0 +1,8 @@
+/*
+  Warnings:
+
+  - You are about to drop the column `userId` on the `Contact` table. All the data in the column will be lost.
+
+*/
+-- AlterTable
+ALTER TABLE "Contact" DROP COLUMN "userId";

packages/database/schema.prisma

@@ -112,14 +112,12 @@ model ContactAttributeKey {
 /// Contacts are environment-specific and can have multiple attributes and responses.
 ///
 /// @property id - Unique identifier for the contact
-/// @property userId - Optional external user identifier
 /// @property environment - The environment this contact belongs to
 /// @property responses - Survey responses from this contact
 /// @property attributes - Custom attributes associated with this contact
 /// @property displays - Record of surveys shown to this contact
 model Contact {
   id            String             @id @default(cuid())
-  userId        String?
   createdAt     DateTime           @default(now()) @map(name: "created_at")
   updatedAt     DateTime           @updatedAt @map(name: "updated_at")
   environment   Environment        @relation(fields: [environmentId], references: [id], onDelete: Cascade)