feat: update script for smoother setup

[ellie]

Many users do not seem to read the docs. So, make the install script handle most of the things that we include in the docs quickstart.

Ensures that the install script still functions as expected in non-interactive environments - setup scripts, ci, etc. Offers a flag just in case this check fails, to force non-interactive setup.

Checks

• I am happy for maintainers to push small adjustments to this PR, to speed up the review cycle
• I have checked that there are no existing pull requests for the same thing

[greptile-apps]

Greptile Summary

This PR upgrades the install script to guide users through history import and sync account setup after installation, with automatic TTY detection and a --non-interactive flag for CI/headless environments.

The bash-preexec curl call properly uses TLS/security flags (--proto '=https' --tlsv1.2 -LsSf), and the [ -t 0 ] || [ -c /dev/tty ] check for TTY detection is reasonable. However, atuin register should redirect from /dev/tty to match the pattern used by other interactive prompts in the script, preventing potential stdin-at-EOF failures in curl | sh pipelines.

_{Last reviewed commit: 1770536}

[greptile-apps]

_{2 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[BinaryMuse]

Overall flow looks good to me; don't know about the stdin stuff greptile raised (I'm probably the worst person to review this 😅)

[ellie]

yeah I think greptile is correct, will double check and try it on a few fresh machines! ty