Fix #37: path display in error message

[BerengarWLehr]

Not sure how to upstream the fix into build directory, could not find correct build information.
Fixes #37

[davidpesce]

Thanks for the report and the fix, both confirmed. The crash reproduces exactly as described: validating a bare filename enters the misplacement branch and parts[-2] is out of range.

One inline suggestion on the message text below.

A regression test would be welcome alongside (tests/test_registry.py holds the validate cases; a bare-filename validate asserting a problem string rather than a traceback). If you'd rather not, we can add it when this lands.

One unrelated note since your example entry shows it: as of camp-tools v0.2.51, security-contact: empty fails schema validation. The field needs an email address or an http(s) URL.

[davidpesce]

Path(*actual.parts[:-2]) drops the directory the message exists to name. For plugins/wrongdir/local_x.yml it prints "under 'plugins/'", but the reader needs to see wrongdir. actual.parent handles every case: . for a bare filename, the real directory otherwise.

Suggested change

	f"file is at {actual.name} under '{Path(*actual.parts[:-2])}/' but component "
	f"file is at {actual.name} under '{actual.parent}/' but component "