feat: collapse plugin runtime to one tier behind a plugin SDK

drizzle/mysql/0026_empty_black_bird.sql

@@ -0,0 +1,3 @@
+ALTER TABLE `plugin_permission_grants` MODIFY COLUMN `granted_by` varchar(255);--> statement-breakpoint
+ALTER TABLE `plugin_permission_grants` ADD `source` text DEFAULT ('admin') NOT NULL;--> statement-breakpoint
+ALTER TABLE `plugins` ADD `last_error` text;