Add missing email validation

[ahmedriad1]

Screen.Recording.2025-10-26.at.5.56.39.PM.mov

I found out creating invites using the organization plugin doesn't validate emails agentset-ai/agentset#34

I looked more into the codebase and found it's missing in other places too. So I made this PR that does the following:

1. Validate email when creating invites (organization plugin)
2. Validate email when creating users as admin (admin plugin)
3. Refactor email validation to use zod instead of manual regex & remove redundant error codes that already exist in BASE_ERROR_CODES (email-otp plugin)

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Summary by cubic

Add email validation to organization invites and admin user creation, and standardize email handling and errors in email-otp. Prevents invalid invites/sign-ups and ensures consistent error messages.

• Bug Fixes

  • Validate emails when creating organization invites.
  • Validate emails when admins create users.
  • Lowercase emails before lookup and creation to prevent duplicates.

• Refactors

  • Replace manual regex with zod email validation in email-otp.
  • Use BASE_ERROR_CODES for INVALID_EMAIL and USER_NOT_FOUND; remove redundant local codes.

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commit: abc5cf8

[cubic-dev-ai]

No issues found across 3 files

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@ahmedriad1 make sure to run pnpm lint:fix!

[ahmedriad1]

@ping-maxwell Done

[ping-maxwell]

cc @himself65 @Bekacru