v0.9.0

Fix hints an agent can act on. Every message and every finding of Report v2 now carries an optional fix object that
says what kind of change would fix it (one of eight kinds, such as add-test or revert-config), with a fixed
sentence per message code or signal id and, on a finding, the path or path:line it already names. The hints are
generic and never lower a gate: verdicts, inputs and the PR comment are unchanged. Report v2 gains only the optional
fix field; no field, input or code was removed or renamed.

Added

• Fix hints: every message and every finding of Report v2 carries an optional fix object (kind, hint and, on a
  finding, target), one of eight kinds and one fixed sentence per message code or signal id, so an agent can tell what
  kind of change would fix a finding. No kind lowers a gate; the PR comment is unchanged.