Loki Mode

Added

• Delegate then notify on done. When a background run (loki start --bg)
  finishes, Loki now writes a durable completion summary and fires a local
  desktop notification, so you can delegate a run, walk away, and be told when
  it is ready. This closes the "async agent" gap for Loki's local-only model
  without any hosted backend or CI.
  • Every terminal state notifies and records a summary: success, max-iterations,
    stopped, failed, and genuinely-blocking pauses (the perpetual-mode auto-clear
    pause is correctly NOT treated as terminal, so a mid-run pause never writes a
    false "done" record).
  • The summary is written to .loki/COMPLETION.txt (human-readable) and
    .loki/state/completion.json (machine-readable): outcome, branch, files
    changed, the exact git diff review command, and task counts. The files are
    always written even when notifications are disabled (they are state, not a
    ping), which is the reliable signal for a detached run with no terminal.
  • Notifications are local OS calls only (macOS osascript, Linux notify-send),
    gated by the existing LOKI_NOTIFICATIONS (default on). Zero network egress.
  • Opt-in LOKI_DELEGATE_BRANCH=1 isolates a run's work on a dedicated
    loki/delegate-<timestamp> branch. Opt-in LOKI_DELEGATE_PR=1 opens a local
    pull request on completion (a gh call from your own machine, never CI, no
    auto-merge), only when you are in a GitHub repo with gh authenticated.
    Both default off; the network calls are bounded with a 30s timeout.