fix(primer): force a Codex command at every fixed slot (bypass warm-up skip gates)

The scheduled primer reused the opportunistic warm-up gates, so the 18:00 slot
(exactly 5h after 13:00, but firing a few hundred ms later) fell just under
minIntervalMs and was silently skipped as no_eligible_accounts — the primer did
not actually fire at every slot. Add a forceAttempt path: the fixed-slot primer
bypasses stagger, post-failure cooldown, min-interval, and per-account
usage/rate-limit filters, attempting a real Codex command on the active account
at every 08/13/18/23 slot and recording success/failure.

Reviewer/arbiter holding stays removed (per user). This does not pin the reset
clock — a trailing window still slides with later usage — but it guarantees the
"simple task at every fixed slot" the user asked for.

Verified: typecheck, build, bundle-smoke; new regression tests (13:00 success
then sub-5h 18:00 still fires; control without forceAttempt is skipped;
forceAttempt bypasses cooldown/stagger) + usage-primer/codex-warmup suites pass.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/usage-primer.test.ts

@@ -71,7 +71,7 @@ describe('usage-primer', () => {
         maxUsagePct: 100,
         maxD7UsagePct: 100,
       }),
-      { ignoreZeroUsageWindow: true },
+      { ignoreZeroUsageWindow: true, forceAttempt: true },
     );
   });
 });