fix: VPS-orchestrated generation reliability — generate --sync, reaper TZ fix, maintenance-cron self-heal (v0.22.1) (#171)

Synchronous --sync CLI tick loop for VPS-driven generation over a held-open SSH session (survives Hostinger's ~10-min background-kill); $sync_mode guard on both tick handlers prevents double-drive; Run_Reaper UTC-vs-site-tz fix; one-shot self-heal migration restoring the maintenance crons that vanished after the 06-15/16 deploy (daily-generation excluded — VPS owns it).

QA: APPROVE @ 0689989 (qa-reviews/prautoblogger/2026-06-23-0689989.md). CEO greenlight 2026-06-22.

Agent-Session: prab-reliability-merge-20260622

tests/unit/Core/GenerationCheckpointRunnerTest.php

@@ -6,6 +6,9 @@
  *   kick_off()         -- schedules cron + writes initial transient, no pipeline call.
  *   on_generate_tick() -- pops ONE idea, reschedules or finalizes; halted run aborts early.
  *
+ * Sync-mode guard tests live in GenerationCheckpointRunnerSyncModeTest.php
+ * (split to comply with the 300-line rule).
+ *
  * @package PRAutoBlogger\Tests\Core
  */
 
@@ -104,7 +107,7 @@ class GenerationCheckpointRunnerTest extends BaseTestCase {
 		);
 	}
 
-	// ── kick_off() ────────────────────────────────────────────────────────
+	// __ kick_off() __________________________________________________________________________
 
 	/**
 	 * kick_off() schedules exactly the ORCHESTRATE cron action and writes
@@ -129,7 +132,7 @@ class GenerationCheckpointRunnerTest extends BaseTestCase {
 		$this->assertTrue( $found_running_transient, 'kick_off() must write a running status transient' );
 	}
 
-	// ── on_generate_tick() ────────────────────────────────────────────────
+	// __ on_generate_tick() __________________________________________________________________
 
 	/**
 	 * An empty queue causes generate tick to finalize without scheduling