chameleon 2.21.0

A feature release that finishes the scoped-down items from the same mid-2026
field review. It deepens the cross-file review gate with a deterministic
signature-contract check, gives the correctness judge the forward direction of
the call graph, and promotes the no-network supply-chain checks from review
prose to a groundable tool. All three are advisory, default-on with a kill
switch, tool-time only (never on a hook hot path), and fail open.

Added

• No-network supply-chain diff checks. A new scan_dependency_changes tool
  parses a branch's manifest/lockfile diff (npm, yarn classic and berry, pnpm,
  Bundler) for four supply-chain signals the pr-review skill previously only
  described as prose: a lockfile entry resolving from a non-registry host, a new
  install-lifecycle script, a non-registry dependency source, and a new direct
  dependency. They return as deterministic findings the round-3 refuter can
  ground against, with no network. The registry CVE audit stays opt-in.
• Deterministic caller-contract signature diff. A new get_contract_breaks
  tool diffs each changed TypeScript/Ruby callable's positional parameter
  contract (merge-base vs HEAD) and flags a narrowing, a new required positional
  argument or an optional one made required, only when committed callers exist.
  This fills the gap the auto-pass router had: a narrowing in a low-importer file
  that slid under the blast-radius gate now routes to a human, and pr-review
  surfaces it as a FIX.
• Forward definition hydration for the correctness judge. The judge already
  read the reverse caller facts (who calls the change). It now also reads the
  forward direction, the signatures of the symbols the change imports, from a new
  committed symbol_signatures.json index (parameter shape, declared TypeScript
  type text, definition location), so the reviewer reads each call site with the
  contract it calls into. Existing profiles pick the index up on their next
  /chameleon-refresh.

Changed

• ts_dump.mjs now records declared parameter and return type annotations on
  callable signatures, best-effort and pure-parse with no type checker, feeding
  the definition-hydration block. The symbol_signatures.json artifact joins the
  trust-hashed profile surface.