v2.0.0

Migration needed: no runtime impact, version-only correction.

• 1.0.9 changed schema_version 2 -> 3 by removing the usage field from plan/file_change records (moved to a new usage record type). Per this project's own versioning rule (design doc 19.2), a schema_version change that isn't purely additive -- a field rename or removal -- requires a MAJOR bump of plugin.json, not a patch release. This release corrects that: no code changes from 1.0.9, version only