v0.19.0

Added

• Added typed execution capability requests and compiled per-stage capability
  grants. Compiled plans now carry grant decisions, enforcement/advisory state,
  evidence requirements, and grant warnings for operator inspection.
• Added runtime pre-dispatch capability gates. Denied or unsupported required
  grants block before runner invocation, approval-required grants create durable
  approval objects, and millrace runs show reports compact grant/support
  summaries for completed or blocked stage results.
• Added millrace approvals ls/show/approve/deny for operator-mediated
  capability decisions, with the same direct-vs-mailbox routing behavior as
  other runtime control actions.
• Added documentation for execution capability policy, approval workflows,
  runner support reporting, compile boundaries, and advisory enforcement
  language.

Changed

• Runner adapters now report contextual capability support so Millrace can
  distinguish runtime-enforced, adapter-enforced, unsupported, and advisory-only
  boundaries instead of implying stronger enforcement than the selected runner
  can actually provide.
• millrace config show, compile show, run inspection, runtime docs, and the
  shipped ops skill now surface execution capability state as part of the normal
  operator evidence trail.

Fixed

• Capability-gated runs now normalize missing capability evidence into a
  recoverable runtime failure instead of relying on generic runner-error
  handling.