Allow register to link existing Meshkee accounts after acknowledgement.

Adds optional acknowledgeExistingAccount and documents the CELL_EXISTS_OTHER_SITE → SMS link flow for storefronts.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/auth/auth.service.ts

@@ -79,7 +79,7 @@ export class AuthService {
         existingUser.passwordHash,
       );
 
-      if (!passwordValid) {
+      if (!passwordValid && !dto.acknowledgeExistingAccount) {
         const otherNames = existingUser.businessCustomers
           .map((item) => item.business.nameFa?.trim() || item.business.name)
           .filter(Boolean);

src/auth/dto/register.dto.ts

@@ -1,4 +1,11 @@
-import { IsEmail, IsOptional, IsString, Matches, MinLength } from 'class-validator';
+import {
+  IsBoolean,
+  IsEmail,
+  IsOptional,
+  IsString,
+  Matches,
+  MinLength,
+} from 'class-validator';
 
 export class RegisterDto {
   @IsString()
@@ -27,4 +34,12 @@ export class RegisterDto {
   @IsString()
   @MinLength(3)
   domain!: string;
+
+  /**
+   * When true, link an existing Meshkee account (other websites) to this tenant
+   * without requiring the existing password. Existing password and profile stay unchanged.
+   */
+  @IsOptional()
+  @IsBoolean()
+  acknowledgeExistingAccount?: boolean;
 }