E2E Testing Framework & Bug Fixes

[fredvisser]

Adds comprehensive end-to-end testing framework and fixes several CLI issues discovered during E2E test development.

✨ Key Changes

📋 E2E Testing Framework (New)

• E2E test suite covering workspace, notebook, user, and DFF commands
• 32 total E2E tests validating real SystemLink API integration
• Interactive setup script (setup_e2e.py) for easy configuration
• Comprehensive test documentation and local-only workflow (no CI automation)

🐛 Bug Fixes

• Fixed pagination issues in CLI commands
• Enhanced error handling in notebook downloads
• Improved JSON response structure handling
• Fixed workspace command output formatting

🔧 Technical Improvements

• Removed nisystemlink-client dependency for better API compatibility
• Enhanced CLI utilities for better error reporting
• Improved universal response handlers
• Updated documentation to reflect manual-only E2E testing

🎯 Testing Strategy

E2E tests are currently designed for local development only - no automated CI runs to avoid SystemLink environment dependencies.