feat: enable keepalive and exit of forward failure to ssh command

[tandem97]

This pull request updates the SSH client invocation to include two options that improve connection reliability and make port-forward setup fail fast on errors:

• ServerAliveInterval=60 — sends keepalive packets every 60 seconds to detect and recover broken connections more promptly.
• ExitOnForwardFailure=yes — causes the ssh client to exit immediately if any requested port forward (local, remote, or dynamic) cannot be established, preventing backgrounded sessions with missing forwards.

Why:

• Prevents long-lived but effectively dead SSH sessions by enabling timely detection of network drops.
• Avoids silent failures where port forwarding appears active while required tunnels never established, which can lead to subtle runtime errors.

[strandnerd]

Hey @tandem97! Thanks for your PR! I'll review this weekend