feat: add export functionality for web API with demo script

- Add export API endpoint POST /web/v1/accounts/export
- Support two export modes: text (data strings) and object (full account objects)
- Automatically set account status to 'exported' during export
- Add comprehensive demo script that uploads, exports and verifies functionality
- Update API documentation with export endpoint details
- Add TypeScript types for export functionality

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,91 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Development Commands
+
+```bash
+# Development
+npm run dev          # Start development server with tsx watch
+npm run build        # Compile TypeScript to JavaScript
+npm start           # Run the production build
+
+# Database Operations
+npm run db:create    # Create database if it doesn't exist
+npm run db:generate  # Generate Drizzle migration files
+npm run db:migrate   # Run database migrations
+npm run db:studio    # Open Drizzle Studio (database management UI)
+npm run db:setup     # One-command database setup (create + migrate)
+```
+
+## Architecture Overview
+
+This is a lightweight account management platform built with TypeScript, Fastify, and PostgreSQL. The system uses a **single table design** with the `accounts` table storing all account data.
+
+### Core Design Principles
+- **Single Table Architecture**: All account data stored in one `accounts` table with proper indexing
+- **Dual API Design**: Separate optimized APIs for automation scripts (`/s/v1/`) and web management (`/web/v1/`)
+- **Concurrent Safety**: Account locking mechanism prevents simultaneous access to the same account
+- **Background Jobs**: Automatic cleanup of stale locks via scheduled tasks
+
+### Key Components
+
+**Database Layer** (`src/db/`):
+- `schema.ts`: Single accounts table with unique constraints on platform+customId
+- `index.ts`: PostgreSQL connection using Drizzle ORM
+
+**Core Business Logic** (`src/core/AccountService.ts`):
+- Account acquisition with automatic locking
+- Status management and batch operations  
+- Statistics generation and stale lock cleanup
+- All database operations are transactional where needed
+
+**API Routes**:
+- `src/api/v1/script/actions.ts`: Lightweight script API for automation
+- `src/api/v1/web/accounts.ts`: Full-featured web management API
+- `src/api/v1/web/stats.ts`: Statistics and analytics endpoints
+
+**Background Jobs** (`src/jobs/staleLockCleanup.ts`):
+- Automatic cleanup of accounts locked longer than `LOCK_TIMEOUT_MINUTES`
+
+### Database Schema
+
+The `accounts` table structure:
+- `id`: Primary key (serial)
+- `ownerId`: Account owner identifier
+- `platform`: Platform name (e.g., "twitter", "facebook")
+- `customId`: Custom identifier for the account
+- `data`: JSON data storage for account information
+- `status`: Current status ("available", "locked", "failed", etc.)
+- `notes`: Optional notes field
+- `lockedAt`: Timestamp when account was locked
+- Unique constraint: `platform + customId`
+- Indexes on: `ownerId + status`, `platform + ownerId`
+
+### API Patterns
+
+**Script API** (`/s/v1/{ownerId}/`): GET-based, optimized for automation
+- `GET /acquire?platform=X&count=N` - Get and lock accounts
+- `GET /update/{accountId}/{status}?notes=X` - Update account status
+- `POST /upload` - Bulk upload/update accounts
+
+**Web API** (`/web/v1/`): POST-based with rich payloads
+- `POST /accounts/list` - Complex filtering, pagination, sorting
+- `POST /accounts/delete-batch` - Bulk delete operations
+- `POST /accounts/update-batch` - Bulk update operations
+
+### Environment Configuration
+
+Required environment variables (see `.env.example`):
+- `DATABASE_URL`: PostgreSQL connection string
+- `PORT`: Server port (default: 3000)
+- `NODE_ENV`: Environment mode
+- `LOCK_TIMEOUT_MINUTES`: Lock timeout duration (default: 5 minutes)
+
+### Development Notes
+
+- The application uses Fastify with full CORS enabled
+- Graceful shutdown handling for SIGTERM/SIGINT
+- Structured logging with different levels for dev/prod
+- Health check endpoint at `/health`
+- All API responses use standardized format from `lib/apiResponse.ts`