v0.6.0

Added

• proposal-lifecycle-shared.yml reusable workflow: the contract for the
  five-job proposal lifecycle (apply, reject, distill, rework,
  propose) described in #11, with self-gating, an input-invariant check,
  and per-comment/per-repository concurrency groups. Domain logic for each
  action is not implemented yet — this release ships the contract and
  reporting scaffold only.
• actions/telegram-notify composite action: optionally report a job's
  triggered action and outcome to a Telegram chat (#46). Opt-in per
  consumer; a missing chat id/bot token is a no-op and a delivery failure
  never fails the calling job.