fix: Make sure remote exists before trusting a clone dir

[lukemassa]

what

If we cannot find the expected remote in the cloned dir, do not use that clone dir, and instead force a reclone.

why

In order versions of the code we called the remote head. If you have a checkout created by an old version of the code and then run the new code, we don't want it to reuse that repo we want it to do a full reclone

tests

If I create a PR with 0.37.0, then restart w this branch, it'll see the old remote named head but can't find the new remote, which should be called source, and fails. This falls back to a full reclone, which is the simplest thing to do in the situation.

{"level":"error","ts":"2026-01-06T23:58:11.034-0500","caller":"events/working_dir.go:112","msg":"An error occurred attempting to reuse the clone dir, falling back to forced clone. This is likely a bug please report: cannot find remote source

references

Closes: #6065