test(registry): verify owner navigation paths exist
Summary
Make the existing owner-file projection test require every navigation path to exist, including extracted descriptor-family files. A family rename that leaves the old path behind now fails with that stale path in the assertion.
One test file changed. No production metadata, package exports, family list or eager closure changes. This checks path existence; it does not infer that every existing file owns a command. Follow-up to merged #4076 and its review; part of #4045.
Validation
Head: d528bfeaa8385dee35db2d859d900d69926566ad.
Frozen install/build, all three focused owner-file tests and full format passed. Exact-head affected validation passed all six selected checks: format, lint, typecheck, layering, Fallow and related tests. Receipt run-uOEjiR, exactCommit: true. CI retains its additional obligations.