feat: wave 2 eval harness with lm-as-judge and cli command

New eval framework:
- eval/dataset.json: 20 frozen peptide topic eval items
- class-opik-eval-scorer.php: LLM-as-judge using Gemini Flash 1.5
  Scores on: scientific_signal, readability, style_adherence (0-10)
- class-opik-eval-runner.php: orchestrator for full eval pass
  Loads dataset, runs generation (no publish/images), scores, pushes to Opik
  run(int $limit = 0, bool $dry_run = false): array
- class-wp-cli-commands.php: registers wp prautoblogger opik:eval
  Flags: --limit=<n> (default 0 = all), --dry-run (score only)

Features:
- Rate limiting: 500ms between items
- Cost tracking: eval judge calls logged to opik_eval_judge stage
- Dry-run mode: test locally without Opik API push
- Experiment naming: prautoblogger-eval-v<VERSION>-<YYYY-MM-DD>

All files <= 300 lines. Version 0.13.0. Ready for PR.

includes/admin/class-wp-cli-commands.php

@@ -0,0 +1,72 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * WP-CLI commands for PRAutoBlogger.
+ *
+ * Registers custom wp-cli commands exposed to the plugin.
+ */
+class PRAutoBlogger_WP_CLI_Commands {
+
+	/**
+	 * Register WP-CLI commands.
+	 *
+	 * Called on plugins_loaded hook.
+	 */
+	public static function register(): void {
+		if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
+			return;
+		}
+
+		// Command: wp prautoblogger opik:eval
+		\WP_CLI::add_command(
+			'prautoblogger opik:eval',
+			array( self::class, 'opik_eval_command' ),
+			array(
+				'shortdesc' => 'Run Opik evals on the frozen dataset',
+				'synopsis'  => array(
+					array(
+						'type'        => 'assoc',
+						'name'        => 'limit',
+						'description' => 'Max items to run (0 = all)',
+						'optional'    => true,
+						'default'     => '0',
+					),
+					array(
+						'type'        => 'flag',
+						'name'        => 'dry-run',
+						'description' => 'Skip Opik API push; score locally only',
+						'optional'    => true,
+					),
+				),
+			)
+		);
+	}
+
+	/**
+	 * Run eval on the frozen dataset.
+	 *
+	 * @param array $args Positional args (unused).
+	 * @param array $assoc_args Associative args: limit, dry-run.
+	 *
+	 * @return void
+	 */
+	public static function opik_eval_command( array $args, array $assoc_args ): void {
+		// Check if Opik is enabled.
+		if ( empty( PRAUTOBLOGGER_OPIK_API_KEY ) || empty( PRAUTOBLOGGER_OPIK_WORKSPACE ) ) {
+			if ( ! isset( $assoc_args['dry-run'] ) ) {
+				// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_echo -- CLI output
+				echo "Warning: Opik is not configured. Running with --dry-run only.\n";
+				$assoc_args['dry-run'] = true;
+			}
+		}
+
+		$limit   = absint( $assoc_args['limit'] ?? 0 );
+		$dry_run = isset( $assoc_args['dry-run'] );
+
+		$runner = new PRAutoBlogger_Opik_Eval_Runner();
+		$result = $runner->run( $limit, $dry_run );
+
+		exit( $result['items_run'] > 0 ? 0 : 1 );
+	}
+}