Allow Selection of SSH Key When Registering Account

[nandanito]

Problem
Currently, user registration on itter.sh via SSH appears to use the first or default SSH public key available on the client system. This can create issues for users who manage multiple SSH keys for different accounts or purposes.

Suggested Feature

• Allow users to select a specific SSH key during the registration process.
• Document in the setup instructions how to specify which SSH key the client should use (for example, by using the -i option with the ssh command).
• If possible, prompt the user or provide clearer feedback when an unexpected key is used.

Benefits

• Enhances usability for advanced users who maintain multiple SSH identities.
• Reduces confusion or registration failures caused by the wrong SSH key being submitted.
• Makes the onboarding process friendlier, especially for those with complex SSH configurations.

Example
Consider updating your documentation to recommend:

ssh -i /path/to/specific_key.pub register:USERNAME@app.itter.sh

Or, detect multiple keys and guide the user if a mismatch is detected.

Additional Context

Many users manage keys for work, personal, and test environments, and greater flexibility at registration will improve the developer experience.