RESULT: SUCCESS

FILES CHANGED:
- jq_interpreter/evaluator.py
- jq_interpreter/parser.py
- tests/test_data_003_entries_containment.py

SUMMARY:
Implemented `keys_unsorted`, `in`, `inside`, `to_entries`, and `from_entries`; corrected key handling and builtin registration. Added focused tests.

Verification: 149 tests passed; DATA-003 conformance passed 26/26 with zero failures/errors.

BLOCKERS:
- None