Create Monthly Summary Report Notebook

[pyang4s]

Description:
Create a new Jupyter notebook (monthly_report.ipynb) that generates a comprehensive monthly financial summary.

Acceptance Criteria:

• Create new notebook in notebooks/ directory
• Include monthly income summary by category
• Include monthly expense summary by category
• Calculate savings rate for the month
• Add visual comparison charts (income vs expenses)
• Allow user to specify month/year parameters
• Document usage in notebooks/README.md

Estimated Effort: 3-4 hours