v0.13.0

Minor Changes

• 17375fd: Publish the skill-action frontmatter contract: a new ./action-frontmatter
  export with Zod schemas for ActionFrontmatter and its sub-schemas
  (DomainEnum, UxModeEnum, RunBinding, Trigger, CapabilityEnum,
  SetupSpec). This is the source-of-truth shape for an Atelier skill action's
  YAML frontmatter (the block between the leading --- fences of an
  actions/*.md file). Mirrors the Rust loader in royalti-io/ikenga
  (src-tauri/src/pkg/skill_actions.rs) — same lockstep convention as
  manifest.ts ↔ manifest.rs. Conformance-tested against every installed Atelier
  action file. Additive; no existing export changes.
• 4d7bc7d: PermissionsSchema gains engine (string[] of engine scopes, e.g. "invoke") —
  previously undeclarable, so the shell's engine:invoke gate on
  host.sendToActiveSession could never pass for any pkg. Mirrors the shell
  manifest.rs Permissions.engine field (lockstep).