feat(phase2b): P2b.2 — bounded Editorial_Loop (#179, v0.29.0)

Additive: iterative editor↔writer loop bounded by editorial_max_rounds (default 3), escalates to Review Queue on exhaustion, records each round; behind interface, Authority-only (live path untouched). Also deletes dead class-research-dedup.php + repairs ARCHITECTURE.md. QA APPROVE 16035fa; CI green (VPS-verified).

Agent-Session: prab-phase2b-2-merge

includes/providers/interface-editorial-loop.php

@@ -0,0 +1,50 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Contract for the Authority-tier editorial loop.
+ *
+ * Wraps the Chief_Editor review into a bounded iterative loop (≤
+ * `editorial_max_rounds`) where the editor critiques and the writer
+ * revises until the article is approved or rounds are exhausted.
+ *
+ * @see core/class-editorial-loop.php  — Primary implementation.
+ * @see ARCHITECTURE.md                — Phase 2b editorial stage design.
+ */
+interface PRAutoBlogger_Editorial_Loop_Interface {
+
+	/**
+	 * Run the iterative editorial loop for one article.
+	 *
+	 * Each round: editor critiques → writer revises → if approved, stop.
+	 * After max rounds without approval the article is escalated to the
+	 * Review Queue (saved as draft) and an empty string is returned so
+	 * the caller can detect the escalation.
+	 *
+	 * Side effects: multiple LLM API calls (reserved via cost governor),
+	 * `run_stages` + `run_decisions` DB writes per round.
+	 *
+	 * @param string                     $run_id   Pipeline run UUID.
+	 * @param string                     $item_key Article-scoped stage key.
+	 * @param string                     $content  Initial draft HTML from the writer.
+	 * @param PRAutoBlogger_Article_Idea $idea     The article idea under review.
+	 * @param PRAutoBlogger_Cost_Tracker $cost_tracker Pipeline cost tracker.
+	 * @return string Approved (or final-revised) HTML, or '' on escalation.
+	 */
+	public function run(
+		string $run_id,
+		string $item_key,
+		string $content,
+		PRAutoBlogger_Article_Idea $idea,
+		PRAutoBlogger_Cost_Tracker $cost_tracker
+	): string;
+
+	/**
+	 * Whether the last run() call resulted in an escalation to the Review Queue.
+	 *
+	 * Callers must check this after run() returns ''.
+	 *
+	 * @return bool
+	 */
+	public function was_escalated(): bool;
+}