fix: add services/opik/ to autoloader — v0.12.3

class-autoloader.php listed services/ as a scan directory but not
services/opik/, where all four Opik classes live. Composer's classmap
covers includes/ recursively so PHPUnit passed; the WP runtime autoloader
fatals on first Opik class reference in production.

Root cause: the subdirectory was not added to the explicit $directories
array when the opik/ subdirectory was created in Wave 1.

Adds services/opik/ to the scan list. Bumps to v0.12.3.

includes/class-autoloader.php

@@ -30,6 +30,7 @@ class PRAutoBlogger_Autoloader {
 		'models/',
 		'frontend/',
 		'services/',
+		'services/opik/',
 		'ajax/',
 	);