refactor: simplify codebase with unified patterns and reduced duplication

- unify ChatConfigService setters into generic setPermission method
- replace PermissionService switch statements with data-driven checkers map
- deduplicate config.ts callback handlers via loop-based registration (414→254 lines)
- extract shared updateChatCommands utility from role-add/role-delete
- add proper generics to chunk utility, fix mention loop indexing
- extract isHiddenAdmin helper and ANONYMOUS_ADMIN_ID constant in perms
- remove debug console.logs, standardize arrow exports and type imports
- add roleAdminPermission schema and migration

drizzle/0002_bored_stephen_strange.sql

@@ -0,0 +1,2 @@
+CREATE TYPE "public"."role_admin_permission" AS ENUM('everyone', 'all_admins', 'only_owner');--> statement-breakpoint
+ALTER TABLE "chat_configs" ADD COLUMN "role_admin_permission" "role_admin_permission" DEFAULT 'all_admins' NOT NULL;