feat: Wave 2 eval harness + image pipeline instrumentation (v0.13.0)

Closes #119

- Extract PRAutoBlogger_Image_Scene_Parser from image prompt builder (331→300 lines)
- Add frozen eval dataset (20 peptide topics at eval/dataset.json)
- Add LLM-as-judge scorer (gemini-flash-1.5 via OpenRouter, 3 axes)
- Add eval runner orchestrator with dry-run and Opik push support
- Add WP-CLI command: wp prautoblogger opik:eval [--limit=<n>] [--dry-run]
- Add image pipeline Opik instrumentation (image_prompt_rewrite span)
- Add content generator eval mode (suppresses publish + image gen)
- Version: v0.13.0

includes/class-prautoblogger.php

@@ -55,6 +55,7 @@ class PRAutoBlogger {
 		$this->register_cron_hooks();
 		$this->register_frontend_hooks();
 		$this->register_ajax_hooks();
+		$this->register_cli_hooks();
 
 		/** Fires after PRAutoBlogger has finished registering all hooks. */
 		do_action( 'prautoblogger_loaded' );
@@ -294,6 +295,11 @@ class PRAutoBlogger {
 		return $schedules;
 	}
 
+	/** Register WP-CLI commands. */
+	private function register_cli_hooks(): void {
+		PRAutoBlogger_WP_CLI_Commands::register();
+	}
+
 	/**
 	 * Block false update notifications from wordpress.org.
 	 * Our plugin slug may collide with a different plugin in the directory.