fix(list): skip unresolvable entries when dating changes (#1866)

* fix(list): skip unresolvable entries when dating changes

To sort changes by recency, list stats every file inside each change,
and any entry it could not stat failed the whole command. A dangling
symlink, such as the .#file lock Emacs keeps beside every file with
unsaved edits, or a symlink loop made list exit 1 and list --json report
no changes at all.

Skip an entry that no longer resolves (ENOENT or ELOOP) when computing a
change's last-modified time. Valid symlinks are dated as before, and any
other error still fails the listing.

* test(list): pin that a permission error still fails the listing

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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Co-authored-by: Clay Good <hi@claygood.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>