Chameleon

Chameleon now captures the contract a base class or decorator implies, not just
its name. An ActiveInteraction subclass declares typed filters and defines
#execute; a NestJS service carries @Injectable and extends a base. Before
this, only the base/decorator was recorded and the body shape was invisible, so
new code missed the convention and review caught it. The contract is surfaced on
every edit.

Added

• Per-archetype class_contract convention. Derived at bootstrap/refresh: the
  repo-specific DSL macros (Ruby), class decorators (TypeScript), required methods,
  and base that an archetype's classes share. It requires a structural anchor (a
  dominant base or decorator) and is measured only over the cohort carrying that
  anchor, so a co-located helper or error class never dilutes it. Surfaced in the
  edit-time echo (Contract: extends ActiveInteraction::Base, macros object, define execute)
  and a SessionStart CONTRACT: section. Advisory only.
• Custom-DSL extraction. The Ruby dump now emits receiverless class-body macro
  calls, generalizing beyond the fixed Rails allowlist (ActiveInteraction,
  dry-validation, Grape, and other gem DSLs). The TypeScript dump now emits class
  decorators and extends/implements, which were dropped entirely before.
• /chameleon-auto-idiom contract mining. The skill now mines the body contract
  a framework base/decorator implies, and idiom coverage exposes
  covered.class_contract with a carve-out so an idiom that explains the contract is
  not suppressed as a bare restatement of the inheritance convention.

Changed

• Existing profiles pick this up on the next /chameleon-refresh: the engine-version
  bump forces a full re-derive even for production-pinned repos with an unchanged
  tip, and auto-refresh triggers it on the next session. Trust is preserved when the
  archetype/canonical/rule/idiom artifacts are unchanged, so no manual re-trust is
  needed in the common case.

Fixed

• The archetype-rename path now carries the class_contract section to the new
  archetype key alongside the other per-archetype conventions.