Lock identity for accessory VFX rows is now the model source path
(dataset:group/subgroup/file.mdl) rather than the config-derived
presentation key. Config-only edits (key_format, delimiter, case,
strip_prefixes) no longer reshuffle row IDs.
Adds: accessoryVisualeffectLockKey, hasKey helper, stale pruning loop
(managed keys with no live entry are freed), and one-time cutover remap
(old config-derived key in historical lock → new model-path key, with
the old key pruned). autogenConsumerManagedLockKeyMatcher is now
config-independent (dataset prefix + first path segment ∈ policy groups).
Updates autogen_manifest_file_test.go and topdata_test.go lock-key
assertions to match the new model-path scheme.
archvillainette