perf(2meet-data-optimizer): keep cached routed counts across unrelated post meta writes

- cached counts followed posts' last_changed, which WordPress moves on any
  post meta write; themes write meta on page views (on dev36 Blocksy saved a
  dynamic-CSS descriptor for each listing a crawler visited), so the cache
  was invalidated every few seconds and keyword/filter searches recounted
- counts now follow their own last_changed group (tmdo_posts), bumped on
  clean_post_cache (post saved or deleted; hooked in every mode) and on flat
  writes through the Hook Bus, plus terms' last_changed; a routed search reads
  no unmanaged meta
- Verify: PostQueryRouterFoundRowsTest (unrelated meta write keeps the count,
  save or flat write recounts), integration 588, unit 703, phpcs, stan;
  dev36 front-end
- PR: PR-117 (2.3 acceptance)

includes/class-tmdo-core.php

@@ -261,6 +261,9 @@ class TMDO_Core {
 			$post_router = new TMDO_Post_Query_Router();
 			$post_router->register_hooks();
 		}
+		if ( class_exists( 'TMDO_Post_Query_Router' ) ) {
+			add_action( 'clean_post_cache', array( 'TMDO_Post_Query_Router', 'bump_count_version' ) );
+		}
 
 		// Zone B: Warm cleanup cron handler.
 		add_action( 'wpdo_warm_cleanup', array( $this, 'cleanup_warm_zone' ) );