refactor: reorganize package exports under namespaced paths

- Prefix feature exports with `features/` (auth, admin, provider)
- Prefix shared exports with `shared/` (components, icons, lib, config, logger, rate-limit)
- Add new explicit exports for `shared/logger`, `shared/config`, and `shared/rate-limit`
- Update internal imports to use package self-referencing (`@zen/core/shared/*`) instead of relative paths

src/features/auth/lib/session.js

@@ -3,7 +3,7 @@
  * Handles user session creation, validation, and deletion
  */
 
-import { create, findOne, deleteWhere, updateById } from '../../../core/database/crud.js';
+import { create, findOne, deleteWhere, updateById } from '@zen/core/database';
 import { generateToken, generateId } from './password.js';
 
 /**