Chameleon

Fixed

• Refresh now repairs a stale-schema generated index instead of noop-preserving
  it forever. The repair predicate (_profile_needs_rederive) validated the
  four generated indexes (calls_index.json, function_catalog.json,
  symbol_signatures.json, counterexamples.json) as parseable JSON objects
  only, but each loader hard-rejects a foreign schema_version — so an index
  left behind by an older engine (e.g. a pre-v2.41 calls_index at schema 1)
  read as "healthy" to refresh while every consumer silently got zero facts:
  judge caller grounding, the duplication prefilter, get_callers
  (calls-index-stale), and the cross-file checks. Doctor detected the state
  and get_callers said "run /chameleon-refresh", but the recommended refresh
  noop-preserved the damage — a detect-recommend-repair loop with the repair
  missing. The predicate now mirrors each loader's own schema gate via its
  exported constant (counterexamples honors its readable-legacy set, so a v1
  file that still loads is not flagged), so a future schema bump propagates
  automatically. Found by the Ruby QA battery against a real pre-v2.41 fixture;
  verified end-to-end: the same refresh that previously nooped now re-derives
  and the battery went 65/66 to 66/66.