feat(phase2b): P2b.4 — tier routing + Authority pipeline + citation/imagery gates (#181, v0.31.0)

Authority_Pipeline orchestrator (research→curate→draft→editorial→seo→publish gate) + per-category tier router behind master flag prautoblogger_authority_pipeline_enabled (DEFAULT OFF — zero behavior change until enabled). Cost-ceiling halts→hold; citation + imagery gates. QA APPROVE b086079; CI green (phpcs+phpunit VPS-verified).

Agent-Session: prab-phase2b-4-merge

prautoblogger.php

@@ -9,7 +9,7 @@
  * Plugin Name:       PRAutoBlogger
  * Plugin URI:        https://peptiderepo.com/prautoblogger
  * Description:       Monitors social media for trending topics, generates SEO-friendly blog posts using AI, and publishes them on a daily schedule with full cost tracking and self-improvement metrics.
- * Version:           0.30.0
+ * Version:           0.31.0
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | Defined here so every file in the plugin can reference paths, versions,
 | and limits without magic strings.
 */
-define( 'PRAUTOBLOGGER_VERSION', '0.30.0' );
+define( 'PRAUTOBLOGGER_VERSION', '0.31.0' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.4.0' );  // No schema change in v0.30.0 (Seo_Stage is additive code only).
 define( 'PRAUTOBLOGGER_DEFAULT_RUN_CEILING_USD', 0.50 );
 define( 'PRAUTOBLOGGER_DEFAULT_REQUEST_JSON_RETENTION_DAYS', 14 );