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.plan.md

@@ -1,71 +1,48 @@
-# bunq API Client Implementation Plan
+# Migration Plan: @push.rocks/smartrequest
 
-cat /home/philkunz/.claude/CLAUDE.md
+To re-read CLAUDE.md: `cat ~/.claude/CLAUDE.md`
 
-## Phase 1: Remove External Dependencies & Setup Core Infrastructure
+## Objective
+Migrate the Bunq HTTP client from native `fetch` to `@push.rocks/smartrequest` to leverage built-in rate limiting, better error handling, and improved maintainability.
 
-- [x] Remove @bunq-community/bunq-js-client dependency from package.json
-- [x] Remove JSONFileStore and bunqCommunityClient from bunq.plugins.ts
-- [x] Create bunq.classes.apicontext.ts for API context management
-- [x] Create bunq.classes.httpclient.ts for HTTP request handling
-- [x] Create bunq.classes.crypto.ts for cryptographic operations
-- [x] Create bunq.classes.session.ts for session management
-- [x] Create bunq.interfaces.ts for shared interfaces and types
+## Tasks
 
-## Phase 2: Implement Core Authentication Flow
+### 1. Setup
+- [x] Install @push.rocks/smartrequest dependency using pnpm
+- [x] Update ts/bunq.plugins.ts to import smartrequest
 
-- [x] Implement RSA key pair generation in crypto class
-- [x] Implement installation endpoint (`POST /v1/installation`)
-- [x] Implement device registration (`POST /v1/device-server`)
-- [x] Implement session creation (`POST /v1/session-server`)
-- [x] Implement request signing mechanism
-- [x] Implement response verification
-- [x] Add session token refresh logic
+### 2. Refactor BunqHttpClient
+- [x] Replace fetch-based makeRequest method with SmartRequest implementation
+- [x] Preserve all custom headers (X-Bunq-*)
+- [x] Maintain request signing functionality
+- [x] Keep response signature verification
+- [x] Map LIST method to GET (SmartRequest doesn't have LIST)
+- [x] Replace manual retry logic with built-in handle429Backoff()
 
-## Phase 3: Update Existing Classes
+### 3. Error Handling
+- [x] Ensure BunqApiError is still thrown for API errors
+- [x] Map SmartRequest errors to appropriate error messages
+- [x] Preserve error message format for backward compatibility
 
-- [x] Refactor BunqAccount class to use new HTTP client
-- [x] Update BunqMonetaryAccount to work with new infrastructure
-- [x] Update BunqTransaction to work with new infrastructure
-- [x] Add proper TypeScript interfaces for all API responses
-- [x] Implement error handling with bunq-specific error types
+### 4. Testing
+- [x] Run existing tests to ensure no regression (tests passing)
+- [x] Verify rate limiting behavior works correctly
+- [x] Test signature creation and verification
+- [x] Ensure all HTTP methods (GET, POST, PUT, DELETE, LIST) work
 
-## Phase 4: Implement Additional API Resources
+### 5. Cleanup
+- [x] Remove unused code from the old implementation (manual retry logic removed)
+- [x] Update any relevant documentation or comments
 
-- [x] Create bunq.classes.user.ts for user management
-- [x] Create bunq.classes.payment.ts for payment operations
-- [x] Create bunq.classes.card.ts for card management
-- [x] Create bunq.classes.request.ts for payment requests
-- [x] Create bunq.classes.schedule.ts for scheduled payments
-- [x] Create bunq.classes.draft.ts for draft payments
-- [x] Create bunq.classes.attachment.ts for file handling
-- [x] Create bunq.classes.export.ts for statement exports
-- [x] Create bunq.classes.notification.ts for notifications
-- [x] Create bunq.classes.webhook.ts for webhook management
+## Implementation Notes
 
-## Phase 5: Enhanced Features
+### Key Changes
+1. Replace native fetch with SmartRequest fluent API
+2. Use built-in handle429Backoff() instead of manual retry logic
+3. Leverage SmartRequest's response methods (.json(), .text())
+4. Maintain all Bunq-specific behavior (signatures, custom headers)
 
-- [x] Implement pagination support for all list endpoints
-- [x] Add rate limiting compliance
-- [x] Implement retry logic with exponential backoff
-- [x] Add request/response logging capabilities
-- [x] Implement webhook signature verification
-- [x] Add OAuth flow support for third-party apps
-
-## Phase 6: Testing & Documentation
-
-- [ ] Write unit tests for crypto operations
-- [ ] Write unit tests for HTTP client
-- [ ] Write unit tests for all API classes
-- [ ] Create integration tests using sandbox environment
-- [x] Update main README.md with usage examples
-- [x] Add JSDoc comments to all public methods
-- [x] Create example scripts for common use cases
-
-## Phase 7: Cleanup & Optimization
-
-- [x] Remove all references to old bunq-community client
-- [x] Optimize bundle size
-- [x] Ensure all TypeScript types are properly exported
-- [x] Run build and verify all tests pass
-- [x] Update package version
+### Risk Mitigation
+- All Bunq-specific logic remains unchanged
+- Public API of BunqHttpClient stays the same
+- Error handling maintains same format