feat(export): add buffer download methods to ExportBuilder

- Added download() method to get statements as Buffer without saving to disk
- Added downloadAsArrayBuffer() method for web API compatibility
- Enhanced documentation for getAccountStatement() method
- Updated README with comprehensive examples
- No breaking changes, backward compatible

readme.md

@@ -1,6 +1,34 @@
 # @apiclient.xyz/bunq
+
+[![npm version](https://img.shields.io/npm/v/@apiclient.xyz/bunq.svg)](https://www.npmjs.com/package/@apiclient.xyz/bunq)
+[![TypeScript](https://img.shields.io/badge/TypeScript-Ready-blue.svg)](https://www.typescriptlang.org/)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
 A powerful, type-safe TypeScript/JavaScript client for the bunq API with full feature coverage
 
+## Table of Contents
+- [Features](#features)
+- [Stateless Architecture](#stateless-architecture-v400)
+- [Installation](#installation)
+- [Quick Start](#quick-start)
+- [Core Examples](#core-examples)
+  - [Account Management](#account-management)
+  - [Making Payments](#making-payments)
+  - [Payment Requests](#payment-requests)
+  - [Draft Payments](#draft-payments-requires-approval)
+  - [Card Management](#card-management)
+  - [Webhooks](#webhooks)
+  - [File Attachments](#file-attachments)
+  - [Export Statements](#export-statements)
+  - [Session Management](#stateless-session-management)
+  - [User Management](#user-management)
+- [Advanced Usage](#advanced-usage)
+- [Security Best Practices](#security-best-practices)
+- [Migration Guides](#migration-guide)
+- [Testing](#testing)
+- [Requirements](#requirements)
+- [License](#license-and-legal-information)
+
 ## Features
 
 ### Core Banking Operations
@@ -26,6 +54,7 @@ A powerful, type-safe TypeScript/JavaScript client for the bunq API with full fe
 - ⚡ **Promise-based** - Modern async/await support throughout
 - 🛡️ **Type Safety** - Compile-time type checking for all operations
 - 📚 **Comprehensive Documentation** - Detailed examples for every feature
+- 🔄 **Robust HTTP Client** - Built-in retry logic and rate limit handling
 
 ## Stateless Architecture (v4.0.0+)
 
@@ -405,6 +434,44 @@ await new ExportBuilder(bunq, account)
   .lastDays(30)
   .includeAttachments(true)
   .downloadTo('/path/to/statement-with-attachments.pdf');
+
+// Get statement as Buffer (no file saving)
+const buffer = await new ExportBuilder(bunq, account)
+  .asPdf()
+  .lastMonth()
+  .download();
+// Use the buffer directly, e.g., send as email attachment
+await emailService.sendWithAttachment(buffer, 'statement.pdf');
+
+// Get statement as ArrayBuffer for web APIs
+const arrayBuffer = await new ExportBuilder(bunq, account)
+  .asCsv()
+  .lastDays(30)
+  .downloadAsArrayBuffer();
+// Use with web APIs like Blob
+const blob = new Blob([arrayBuffer], { type: 'text/csv' });
+
+// Using account's getAccountStatement method for easy month selection
+const statement1 = account.getAccountStatement({
+  monthlyIndexedFrom1: 1,  // Last month (1 = last month, 2 = two months ago, etc.)
+  includeTransactionAttachments: true
+});
+await statement1.asPdf().downloadTo('/path/to/last-month.pdf');
+
+// Or using 0-based indexing
+const statement2 = account.getAccountStatement({
+  monthlyIndexedFrom0: 0,  // Current month (0 = current, 1 = last month, etc.)
+  includeTransactionAttachments: false
+});
+await statement2.asCsv().downloadTo('/path/to/current-month.csv');
+
+// Or specify exact date range
+const statement3 = account.getAccountStatement({
+  from: new Date('2024-01-01'),
+  to: new Date('2024-03-31'),
+  includeTransactionAttachments: true
+});
+await statement3.asMt940().downloadTo('/path/to/q1-statement.sta');
 ```
 
 ### Stateless Session Management
@@ -552,10 +619,6 @@ try {
     error.errors.forEach(e => {
       console.error(`- ${e.error_description}`);
     });
-  } else if (error.response?.status === 429) {
-    // Handle rate limiting
-    console.error('Rate limited. Please retry after a few seconds.');
-    await new Promise(resolve => setTimeout(resolve, 5000));
   } else if (error.response?.status === 401) {
     // Handle authentication errors
     console.error('Authentication failed:', error.message);
@@ -567,6 +630,26 @@ try {
 }
 ```
 
+### Automatic Rate Limit Handling
+
+The library automatically handles rate limiting (HTTP 429 responses) with intelligent exponential backoff:
+
+```typescript
+// No special handling needed - rate limits are handled automatically
+const payments = await Promise.all([
+  payment1.create(),
+  payment2.create(),
+  payment3.create(),
+  // ... many more payments
+]);
+
+// The HTTP client will automatically:
+// 1. Detect 429 responses
+// 2. Wait for the time specified in Retry-After header
+// 3. Use exponential backoff if no Retry-After is provided
+// 4. Retry the request automatically (up to 3 times)
+```
+
 ### Pagination
 
 ```typescript