Add team members: don't include all users in autocomplete

[philipschm1tt]

When you add team members In a publicly available instance of Quepid, the autocomplete feature suggests any user on the platform with their name and email address. This would allow people to to extract the names and email addresses of all users on the instance.

For users and companies that are more reluctant about giving out their data, this behavior is not ideal.
It may be better to either remove the suggestions or use a simple approach where you only show suggestions if the email address has the same domain.

[epugh]

I have a new approach that is in the #1642 branch taht does:

✅ Exact email match: "random@random.com" finds that user (if in allowed scope)
✅ Prefix email match: "random@" finds "random@random.com"
✅ Name substring match: "john" finds "John Doe"
❌ Partial domain: "random@rando" does NOT match "random@random.com"
🔒 Security: Only suggests users from same teams or same email domain
🎨 UI: Email only shows when matched on email, not name

[epugh]

I slacked you a test environment!

[epugh]

Related to #1342

[epugh]

Fixed in #1642