Adds the discovery flag callers have been asking for since ADR-0027.
Short-circuits before the REPL launches; supports both a human-readable
table and `--json` machine output. Drives the loader's existing
`available_packs()` helper.
Bug fix on the way: `available_packs()` was globbing every `*.json`
in the search path, so the Phase-5 companion `<pack_id>.mastery_report.json`
files were leaking into the list as fake packs with empty fields. The
helper now skips any file ending in `.mastery_report.json` and rejects
JSON that lacks the required `schema_version` / `value_axes` fields.
CLI output:
pack_id version ratified description
------------------- ------- -------- -----------
default_general_v1 1.0.0 yes Balanced general identity...
generosity_first_v1 1.0.0 yes Generosity-first specialization...
precision_first_v1 1.0.0 yes Precision-first specialization...
Tests: +3 (CLI table, CLI JSON, companion-file filter regression).
test_identity_packs.py: 23 -> 26. cognition / smoke green.
Docs: docs/identity_packs.md CLI usage block updated; memory
'identity-packs.md' closes that follow-up.