refactor(db): drop option/data migration from DB migrator

Keep dbDelta table schema only. Remove aksrt_basic_settings dual-write,
layout/cms/resource/order/plate option migrators, and part-1 trait.
Plate CPT activation no longer gated on migration flag.

inc/classes/class-aksrt-forum.php

@@ -132,8 +132,8 @@ class AKSRT_Forum {
     }
 
     public function is_plate_cpt_active(): bool {
-        return post_type_exists('aksrt_forum_plate')
-            && (bool) get_option(AKSRT_DB_Migrator::OPT_PLATE_CPT_MIGRATED);
+        // Plate CPT is the native board model; no option migration gate.
+        return post_type_exists('aksrt_forum_plate');
     }
 
     public function get_config(): array {