Lack of support in recovering my profile as an existing vendor (multivendor admin app)

Is your feature request related to a problem? Please describe.
As an existing vendor I'm always frustrated when I could not find my profile using email ID or restaurant name. There is no information how I can recover my profile and I am forced to create my profile again.

Describe the solution you'd like
Provide error message explaining the error and recommend ways to recover the error.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

No files or tests are named. Start by locating the vendor profile lookup and creation flows, including searches by email and restaurant name, then inspect how errors are returned. Done means an existing vendor receives a clear error and recovery guidance instead of being forced to create a duplicate profile.

Written by the indexing model from the issue text.