feat(termux): GitHub ssh enhancements

[practicalli-johnny]

Adding a local SSH public key to GitHub account

 termux-clipboard-set < $HOME/.ssh/id_rsa.pub && xdg-open https://github.com/settings/keys

Cache the SSH key
Termux doesn't run ssh-agent but does support
SSH key caching using the ssha command

ssh -T [email protected]

This command seems to cache for ssh connection but not for git command.

Add key per termux session (untested)

Run the ssh agent manually and add a private key, entering the keys passphrase when prompted.

ssh-agent && \
eval $(ssh-agent) && \
ssh-add ~/.ssh/engineering

Git clients should now use the agent to unlock the key passphrase automatically, removing the need to enter the passphrase each time.

Once a Termux session has ended or a new one created, the agent is no longer running and Git commands will prompt for the passphrase (or the agent is started and key added again).