Reduce idle loop cadence 20–30m -> ~10–15m (pick up work sooner)

§7 pacing + Builder/Adversary prompts: idle/parked sleep lowered to ~10–15 min so the next
unit of work (or a gate claim) is picked up without long gaps. Unchanged: ~4m polling while
a build/deploy is in flight; keep polling something clearly in-flight rather than treating
it as idle; don't spin on a minutes-long build. Adversary aligned to §7 for consistency.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cc-ci-plan/plan.md

@@ -649,7 +649,9 @@ every wake, `git pull --rebase` first, then:
 **Pacing.** Use `/loop` (self-paced) or `ScheduleWakeup`. Most waits here are for things the
 harness can't notify you about — a Drone build, a `nixos-rebuild`, a deploy converging — so poll
 the *specific* thing: while a build/deploy is in flight, re-check on a short cadence (≈4 min) to
-stay cache-warm; when genuinely idle between iterations, sleep longer (20–30 min). Don't burn
+stay cache-warm; when genuinely idle between iterations, sleep ~10–15 min (re-check reasonably
+promptly so the next unit of work is picked up without long gaps — not 20–30 min). But if something
+is clearly still in flight, keep polling *it* rather than treating the iteration as idle; don't burn
 iterations spinning on a build that takes minutes.
 
 **Anti-drift guards.**