feat: v2.1.0 - Add workflow actions, bulk edit, and API enhancements

[mayurrawte]

Summary

• Add primary_workflow_action() for triggering workflow status transitions
• Add secondary_workflow_action() for sub-workflow transitions
• Add bulk_edit() for updating multiple items in a collection at once
• Add connect()/disconnect() for connection management
• Add search() for document search
• Add patch_item() for partial field updates
• Add get_job_status()/set_job_status() for job status operations
• Add get_workflow() for workflow configuration
• Add get_report_view() for report data with date filters
• Add get_exchange_rate() for currency exchange rates
• Add autocomplete() for reference field suggestions
• Add search_location()/get_place_details() for Google Places integration
• Add create_conversation()/get_conversations() for document messaging
• Add upload_file() for file uploads
• Add proper exception classes (ShipthisAPIError, ShipthisAuthError, ShipthisRequestError)
• Add comprehensive type hints and docstrings
• Bump version to 2.1.0 (aligned with JS client)

Test plan

• Verify all new methods work with valid API credentials
• Test error handling for invalid requests
• Test bulk_edit with multiple document IDs
• Test workflow actions with valid workflow configurations