Add Jupyter notebook examples for common workflows

[HzaCode]

Description

Add practical Jupyter notebook examples to help users get started quickly.

Proposed notebooks

1. Basic Analytics Query (examples/01_basic_analytics.ipynb)

   • Connect to DHIS2
   • Query analytics data
   • Convert to DataFrame
   • Basic visualization

2. Data Quality Review (examples/02_data_quality.ipynb)

   • Pull data
   • Run DQR metrics
   • Generate summary report

3. Tracker Events (examples/03_tracker_events.ipynb)

   • Query events
   • Filter and transform
   • Export to CSV

Benefits

• Faster onboarding for new users
• Demonstrate real-world usage
• Easy to copy and modify