feat(M3): re-run engine — replay + rebuild as chained-cron jobs under CPO guardrails

Two operator primitives, both queued (never synchronous — CPO hard
constraint), all mutations in the cron handler after re-validating
eligibility UNDER the generation lock:

- Replay (Stage_Replay + on_replay_job): one governed chat call from the
  latest edited input fork. options_from_body() is the exact inverse of
  build_body()+apply_reasoning_budget() (headroom subtracted back out;
  reasoning pinned explicitly so global-setting drift can't reshape a
  replay). Goes through send_chat_completion -> cost governor reserves
  against the SAME run row (guardrail 4), retry/empty-guard machinery,
  B1 recorder. Fresh output lands in the stage snapshot; downstream
  stale-marked (guardrail 3); human_modified set at execution entry
  (guardrail 2).
- Rebuild (on_rebuild_job): demote target+downstream to pending, re-enter
  Article_Worker with the idea from the stored seed; upstream done stages
  reuse (never re-charged), demoted stages rebuild prompts from CURRENT
  snapshots — how an upstream edit propagates. Decisions recorded while
  rebuilding a human-modified item are flagged.
- Rerun_Eligibility: published/future/private = frozen (guardrail 5,
  server-side); executing runs blocked; editable stages = writer chat
  stages (outline/draft/polish); chain-order downstream sets.
- Run_State::reopen(): atomic terminal->running gate, ceiling
  re-snapshotted from the current setting, accumulated spend NEVER reset.
- Publisher: re-run output refreshes the existing UNPUBLISHED post
  (status preserved — re-runs never publish); published posts untouched.
- Article_Worker persists the exact idea payload as a seed (INSERT-once)
  so rebuilds can't mis-derive item_key and duplicate a post.
- Rerun_Job_Support: queue/lock/budget/status-transient plumbing; jobs
  ride the M1 status transient so the board shows queued->pickup->result.

Agent-Session: engineer-prab-m3-20260612

includes/class-prautoblogger.php

@@ -141,6 +141,11 @@ class PRAutoBlogger {
 			new PRAutoBlogger_Opik_Settings();
 		}
 
+		// v0.20.0 (M3): operator re-run jobs — chained-cron, never synchronous.
+		$rerun_executor = new PRAutoBlogger_Rerun_Executor();
+		add_action( PRAutoBlogger_Rerun_Executor::REPLAY_ACTION, array( $rerun_executor, 'on_replay_job' ), 10, 5 );
+		add_action( PRAutoBlogger_Rerun_Executor::REBUILD_ACTION, array( $rerun_executor, 'on_rebuild_job' ), 10, 4 );
+
 		add_action( 'prautoblogger_generate_from_idea', array( 'PRAutoBlogger_Ideas_Browser', 'on_cron_generate_from_idea' ) );
 		add_action( 'prautoblogger_reap_orphan_research_rows', array( 'PRAutoBlogger_Research_Reaper', 'on_cron' ) );
 		add_action( 'prautoblogger_reap_orphan_research_rows', array( 'PRAutoBlogger_Run_Reaper', 'on_cron' ) );