refactor: decouple core-storage services from static keys and update i18n setup to use configurable storage adapters

packages/core-i18n/README.md

@@ -2,13 +2,13 @@
 
 [← Back to Root](../../README.md)
 
-A highly decoupled, type-safe internationalization engine for the Eigen Monorepo. 
+A highly decoupled, type-safe internationalization engine for the monorepo. 
 
 It uses a **Hybrid Namespace Strategy**:
-1. **Centralized Engine**: Setup, local persistence (`@repo/core-storage`), and global words (`common`).
+1. **Centralized Engine**: Setup, local persistence orchestration, and global words (`common`).
 2. **Decentralized Dictionaries**: Feature-specific translations (`booking`, `billing`) live inside the application modules and are lazy-loaded.
 
-This architecture strictly adheres to **Inversion of Control (IoC)**. The core engine handles local state and performance, but leaves API and networking decisions entirely to the consuming applications.
+This architecture strictly adheres to **Inversion of Control (IoC)**. The core engine handles local state and performance, but leaves API, networking, and storage implementation decisions entirely to the consuming applications.
 
 ---
 
@@ -65,18 +65,29 @@ graph TD
 
 ## 1. App-Level Setup (Bootstrap)
 
-Initialize the engine *before* your React application mounts to prevent UI flashing.
+Initialize the engine *before* your React application mounts to prevent UI flashing. Provide an `I18nStorageAdapter` using Dependency Injection so the core engine can persist the user's language without being tightly coupled to a specific storage implementation.
 
 ```tsx
 // apps/web/src/main.tsx
 import { StrictMode } from 'react';
 import { createRoot } from 'react-dom/client';
 import { setupI18n } from '@repo/core-i18n';
+import { secureStorage, AppStorageKey } from './core/storage';
 import App from './app';
 
 async function bootstrap() {
-  // Synchronously reads preferred language from storage & inits i18next
-  await setupI18n();
+  // Synchronously reads preferred language from injected storage & inits i18next
+  await setupI18n({
+    storageAdapter: {
+      getLanguage: async () => {
+        const stored = await secureStorage.getItem(AppStorageKey.LOCALE);
+        return typeof stored === 'string' ? stored : null;
+      },
+      setLanguage: async (lng: string) => {
+        await secureStorage.setItem(AppStorageKey.LOCALE, lng);
+      },
+    },
+  });
 
   createRoot(document.getElementById('app')!).render(
     <StrictMode><App /></StrictMode>,