Scrum 307 backend make email case insensitive

[bernhaaard]

• uses transforms at dto layer to transform all incoming emails and ensure they are lowercase

[Mohammed87FS]

well done

[Copilot]

Pull Request Overview

This PR ensures that all incoming email addresses are normalized to lowercase to enforce case-insensitivity.

• Updated test cases to expect lowercase emails.
• Added Transform decorators in DTOs using a dedicated normalizeEmail utility.
• Modified the registration strategy to lowercase the email from payload.

Reviewed Changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
backend/src/modules/users/users.service.spec.ts	Updated mock emails in service tests to be all lowercase.
backend/src/modules/users/users.repository.spec.ts	Updated mock emails and search queries in repository tests to be all lowercase.
backend/src/modules/users/dto/update-user.dto.ts	Added Transform decorator on the email property to normalize the email.
backend/src/modules/users/dto/create-user.dto.ts	Added Transform decorator on the email property to normalize the email.
backend/src/modules/requests/supervision/dto/create-supervision-request.dto.ts	Added Transform decorator on the email property to normalize the email.
backend/src/modules/auth/strategies/clerk-registration.strategy.ts	Applied toLowerCase directly on the payload email during registration.
backend/src/modules/admin/dto/supervisors-bulk-import.dto.ts	Added Transform decorator on the email property in the Supervisor DTO.
backend/src/modules/admin/dto/create-admin.dto.ts	Added Transform decorator on the email property to normalize the email.
backend/src/common/utils/email-utils.ts	Added a new utility function to convert emails to lowercase.

[jb-cc]

When I use this branch, and add myself as an admin with CC221012@fhstp.ac.at, and then try to sign up with cc221012@fhstp.ac.at in clerk, it still does not work. and signs me up as a student instead. please take a look again.

The merge-base changed after approval.