feat: Implement multi-language system (ID/EN) for member dashboard

- Create translation files (locales/id.ts, locales/en.ts)
- Add LanguageContext with useLanguage hook
- Add LanguageToggle component in sidebar
- Default language: Indonesian (ID)
- Translate WalletDialog and TransactionDialog
- Language preference persisted in localStorage
- Type-safe translations with autocomplete

Next: Translate remaining pages (Overview, Wallets, Transactions, Profile)

MULTI_LANGUAGE_IMPLEMENTATION.md

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+# Multi-Language Implementation
+
+## Overview
+Implemented a simple, lightweight multi-language system for the member dashboard with Indonesian (default) and English support.
+
+## Features
+- ✅ **Default Language**: Indonesian (ID)
+- ✅ **Optional Language**: English (EN)
+- ✅ **Persistent**: Language preference saved in localStorage
+- ✅ **Easy Toggle**: Language switcher in sidebar footer
+- ✅ **Type-Safe**: Full TypeScript support with autocomplete
+
+## Structure
+
+### Translation Files
+- `/apps/web/src/locales/id.ts` - Indonesian translations
+- `/apps/web/src/locales/en.ts` - English translations
+
+### Context & Hook
+- `/apps/web/src/contexts/LanguageContext.tsx` - Language context provider
+- Hook: `useLanguage()` - Access translations and language state
+
+### Components
+- `/apps/web/src/components/LanguageToggle.tsx` - Language switcher button
+
+## Usage
+
+### In Components
+```typescript
+import { useLanguage } from '@/contexts/LanguageContext'
+
+function MyComponent() {
+  const { t, language, setLanguage } = useLanguage()
+  
+  return (
+    <div>
+      <h1>{t.overview.title}</h1>
+      <p>{t.overview.totalBalance}</p>
+    </div>
+  )
+}
+```
+
+### Translation Structure
+```typescript
+{
+  common: { search, filter, add, edit, delete, ... },
+  nav: { overview, transactions, wallets, profile, logout },
+  overview: { ... },
+  transactions: { ... },
+  wallets: { ... },
+  profile: { ... },
+  // etc
+}
+```
+
+## Implementation Status
+
+### ✅ Completed
+1. Translation files (ID & EN)
+2. Language context & provider
+3. Language toggle component
+4. Sidebar navigation translated
+5. Build & lint passing
+
+### 🔄 Next Steps (To be implemented)
+1. Translate all member dashboard pages:
+   - Overview page
+   - Wallets page
+   - Transactions page
+   - Profile page
+2. Translate dialogs:
+   - WalletDialog
+   - TransactionDialog
+3. Update toast messages to use translations
+4. Test language switching
+
+## Admin Dashboard
+- **Remains English-only** (as requested)
+- No translation needed for admin pages
+
+## Benefits
+- ✅ No external dependencies
+- ✅ Type-safe with autocomplete
+- ✅ Easy to maintain
+- ✅ Fast performance
+- ✅ Can migrate to react-i18next later if needed