fix(gen2-migration): preserve email verification disabled setting (#14810)

[dgandhi62]

Solves #14810.

Issue Summary

The generate step does not preserve the "Email based user registration/forgot password: Disabled" setting from Gen 1. When autoVerifiedAttributes is ["phone_number"] (not ["email"]), the migration tool incorrectly generates loginWith: { email: true } instead of loginWith: { phone: true }, switching verification from SMS to email.

Reasoning

1. The issue reports that Gen 1 apps configured with autoVerifiedAttributes: ["phone_number"] get migrated to loginWith: { email: true }, which changes the verification channel from SMS to email.
2. Read auth.renderer.ts — found the buildLoginWith method which unconditionally emits either email: true or an email options object. It never checks autoVerifiedAttributes to determine whether phone-based verification was configured.
3. The fix needs to check AutoVerifiedAttributes from the fetched user pool config: if it contains phone_number but not email, the user had email verification disabled and we should emit phone: true instead.
4. The options.userPool.AutoVerifiedAttributes array is already available in the render options passed to buildLoginWith.

Solution

• auth.renderer.ts — In buildLoginWith, added a check for isPhoneOnlyVerification (autoVerified includes phone_number but not email). When true, emits loginWith: { phone: true } instead of loginWith: { email: true }. The existing email verification message/subject logic is preserved in the else branch.
• auth.generator.test.ts — Added a new test case 'generates phone login when email verification is disabled' that mocks a user pool with AutoVerifiedAttributes: ['phone_number'] and UsernameAttributes: ['phone_number'], and asserts the generated resource.ts contains loginWith: { phone: true } with email as a required-but-not-verified user attribute.

Example

Input (Gen 1 — cli-inputs.json):

{
  "cognitoConfig": {
    "autoVerifiedAttributes": ["phone_number"],
    "requiredAttributes": ["email"]
  }
}

Output — before fix (resource.ts):

loginWith: {
  email: true,
},

Output — after fix (resource.ts):

loginWith: {
  phone: true,
},
userAttributes: {
  email: {
    required: true,
    mutable: true,
  },
},