feat(confidence-engine): v0.60g1 list investigation summaries
Recover to clean v0.60f then implement only the storage listing contract.
- Add listInvestigations() to provider: enumerate by prefix, project lightweight summary (id, scenario, updatedAt, investigationRevision, reportExists, reportGeneratedFromRevision), sort by updatedAt desc
- Add application-facing wrapper in investigation-storage.js
- Add 8 deterministic tests covering all listing invariants (coexistence, correct IDs, lightweight projection, legacy exclusion, unrelated exclusion, independent update, ordering, malformed skip)
- Fix MockStorageMap WebStorage API compatibility (.length + .key(i))
- Portfolio NOT migrated — that is v0.60g2
robbond
7ba1771bcf