v0.17.6

Added

• Repository.decoded_data_at(ref) returns typed
  DecodedCommittedDataset values with ordinary JSON-like records while
  retaining each committed dataset's key, schema id, record count, and order.
  History traversal accepts branches, tags, full commit ids, and commit-id
  prefixes without changing HEAD or staged state; the raw canonical bytes from
  Repository.data_at(ref) remain available. (#83)