Migrate from Firebase to file-based storage system

- Remove Firebase dependency and all Firebase code
- Implement local file-based storage with encryption
- Create custom authentication system with password hashing
- Add API routes for auth (register/login) and data operations
- Create FileStorageService for server-side file I/O
- Add AuthService for client-side authentication wrapper
- Update all components to use new storage system
- Add comprehensive documentation (FILE_STORAGE.md, MIGRATION_SUMMARY.md)
- Improve security with AES-GCM encryption and SHA-256 password hashing
- Add ErrorBoundary component for better error handling
- Fix multiple bugs: date serialization, transaction deletion, envelope calculations

README.md

@@ -2,19 +2,25 @@
 
 A modern web-based envelope budgeting application built with Next.js, TypeScript, and Tailwind CSS. This app helps you manage your finances using the traditional envelope budgeting method in a digital format.
 
+**🔒 Privacy-First Design**: All your financial data is stored locally on your server in encrypted files. No cloud services, no data sharing, complete control over your information.
+
 ## Features
 
-- **Envelope Management**: Create and manage budget envelopes for different spending categories
-- **Visual Progress Tracking**: See spending progress with color-coded progress bars
-- **Transaction History**: Track and view recent transactions
-- **Data Input Options**:
+- **🔐 Secure Local Storage**: File-based storage with AES-GCM encryption
+- **👤 User Authentication**: Secure sign-up and login with password hashing
+- **💰 Envelope Management**: Create and manage budget envelopes for different spending categories
+- **📊 Visual Progress Tracking**: See spending progress with color-coded progress bars
+- **💳 Account Management**: Support for multiple accounts (checking, savings, credit cards, etc.)
+- **📝 Transaction History**: Track and view recent transactions
+- **📥 Data Input Options**:
   - **Manual Entry**: Add individual transactions with amount, description, date, and envelope assignment
   - **File Import**: Import transactions from bank exports (CSV, OFX, QFX, QBO formats)
-- **Transaction Editing**: Edit existing transactions with full details
-- **Envelope Creation**: Add new budget envelopes with custom colors and allocations
-- **Data Export**: Export all data to CSV or JSON formats for backup or analysis
-- **Budget Overview**: Monitor total allocated, spent, and remaining amounts
-- **Responsive Design**: Works seamlessly on desktop and mobile devices
+- **✏️ Transaction Editing**: Edit existing transactions with full details
+- **🎨 Envelope Creation**: Add new budget envelopes with custom colors and allocations
+- **💸 Get Paid Feature**: Automatically distribute income across envelopes
+- **📤 Data Export**: Export all data to CSV or JSON formats for backup or analysis
+- **📈 Budget Overview**: Monitor total allocated, spent, and remaining amounts
+- **📱 Responsive Design**: Works seamlessly on desktop and mobile devices
 
 ## Getting Started
 
@@ -35,16 +41,42 @@ cd budget
 npm install
 ```
 
-3. Run the development server:
+3. Create environment file:
+```bash
+cp .env.local.example .env.local
+```
+
+4. Generate a secure encryption key:
+```bash
+node -e "console.log(require('crypto').randomBytes(32).toString('hex'))"
+```
+
+5. Update `.env.local` with your encryption key:
+```bash
+ENCRYPTION_KEY=your-generated-key-here
+```
+
+6. Run the development server:
 ```bash
 npm run dev
 ```
 
-4. Open [http://localhost:7654](http://localhost:7654) in your browser.
+7. Open [http://localhost:7654](http://localhost:7654) in your browser.
+
+## Storage System
+
+This application uses a **local file-based storage system** instead of cloud databases:
+
+- All user data stored in `/data` directory as encrypted JSON files
+- User credentials hashed with SHA-256
+- Budget data encrypted with AES-GCM encryption
+- Complete data portability and privacy
+
+For detailed information about the storage system, see [FILE_STORAGE.md](./FILE_STORAGE.md).
 
 ## Available Scripts
 
-- `npm run dev` - Start the development server
+- `npm run dev` - Start the development server on port 7654
 - `npm run build` - Build the project for production
 - `npm run start` - Start the production server
 - `npm run lint` - Run ESLint for code quality checks
@@ -62,21 +94,35 @@ public/                 # Static assets
 
 ## Technologies Used
 
-- **Next.js 16** - React framework with App Router
+- **Next.js 16** - React framework with App Router and API routes
 - **TypeScript** - Type-safe JavaScript
-- **Tailwind CSS** - Utility-first CSS framework
+- **Tailwind CSS 4** - Utility-first CSS framework
 - **React 19** - UI library
+- **Node.js Crypto** - Encryption and password hashing
 - **ESLint** - Code linting
 
 ## How to Use
 
+### First Time Setup
+
+1. **Create Account**: Open the app and click "Sign Up" to create your account
+2. **Setup Wizard**: Follow the guided setup to:
+   - Add your first account (checking, savings, etc.)
+   - Create initial budget envelopes
+   - Set income allocation rules
+3. **Start Budgeting**: Begin tracking your income and expenses
+
+### Daily Use
+
 1. **View Dashboard**: The main page shows your budget overview and envelope cards
 2. **Add Transactions**:
    - **Manual Entry**: Click "Manual Entry" and fill in transaction details
    - **File Import**: Click "Import from File", select your bank export format, and upload the file
+   - **Get Paid**: Use the "Get Paid" feature to record income and automatically distribute to envelopes
 3. **Monitor Envelopes**: Each envelope displays allocated amount, spent amount, and remaining balance
 4. **Track Progress**: Visual progress bars show spending percentage for each envelope
 5. **View Transactions**: Recent transactions are listed with envelope associations
+6. **Manage Accounts**: Switch between different accounts to track multiple bank accounts, credit cards, etc.
 
 ## Data Import