[calvin-archastro]

Merge order: after the pail obj PR (feat/obj-cli) for real use. The runner shells out to pail obj; the integration test falls back to a contract fake (tier2/fakepail) when the pail binary has no obj, so CI is green either way.

What

Task T2.1 (runner daemon) and minimal T2.3: pail-actions runner --store URL --labels a,b [--name ID] [--once], speaking the bucket protocol of docs/actions.md sections 5 and 8.

1. actions/internal/tier2: Go types for every Tier 2 record, path helpers (QueuePath, LeasePath, ResultPath, ...), Store interface, PailStore (pail obj), MemStore (in-memory, with fault injection), FakeClock, fakepail (shell stand-in for pail obj in tests).
2. actions/internal/runner: poll, claim (create or takeover seq+1 by version match, never delete+recreate), 15 s refresh, loss detection (stops all writes, cancels act), cancel marker, progress, log chunks (64 KB or 2 s) then full.log, result at results/.../<seq>, runners/<id>.json heartbeat. act runs a one-job workflow synthesized from the entry; actions/checkout becomes pail clone --at; act github context comes from the entry.
3. actions/RUNNER.md: usage, tests, manual docker command and result, what is left.

Contract change

docs/actions.md section 5.1 only adds optional queue entry keys (runs_on, name, container, services, defaults; github.run_number|actor|head_ref|base_ref) and says steps are the YAML step objects verbatim. No existing field changes.

Tests

1. MemStore unit tests: claim race (8 runners, one wins), takeover bumps seq, live lease not taken, finished job not re-run, refresh failure stops writes only after local expiry, taken-over lease stops writes and leaves the successor's progress alone, cancel marker (before and during), step/skip accounting, log chunking, --once waits and heartbeats.
2. PailStore contract test against the fake pail obj, same suite as MemStore.
3. Integration: real act, host mode, file:// store: success, failure, cancel. Skipped without a pail binary.
4. Docker mode checked by hand (see RUNNER.md).

Not done

Secrets (ignored with a log line), job outputs, artifacts/cache, scaler (T2.2). See RUNNER.md.

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