Trace command package version silent cache misses

[thompsonmj]

Currently, trace silently swallows version-mismatch cache misses. This is conservative but opaque behavior.

trace entry looks for resolution attempts in the current version's cache namespace (resolve_v{version}_{fingerprint}). If the input was resolved under a different version, the namespace doesn't match and the load quietly returns nothing. The user gets "No resolution attempts found for this entry group.", which is the same message whether the entry never resolved, the cache was cleared, or there's a version mismatch.

Some preliminary options:

• Have trace entry report the current version of taxonopy.
• Scan cache_base_dir for resolve_v*_{fingerprint} directories and report which versions have cached data based on relevant input.
• Add a --cache-version flag to let the user point trace at an older namespace explicitly.
• Some combination: show the diagnostic by default, offer the flag for explicit cross-version access.