revert: drop reviewer-holding primer-alignment approach per user direction

The user asked to NOT defer reviewer/arbiter Codex calls, but instead just fire
a simple primer task at each fixed slot independent of the reviewer. That is
already the live behavior (efc8c00: primer fires at 08/13/18/23 KST + the Claude
binary-path fix). Revert the hold/gating work (e324a1b..ef2b26e) so it can't be
deployed; it is preserved on branch backup/primer-hold-work in case the 08:00
overnight-exhaustion gap later warrants a minimal quiet window.

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, isPrimer: true },
+      { ignoreZeroUsageWindow: true },
     );
   });
 });