Update date format from YYYY-MM-DD to DD MMM, YYYY for Bookkeeper #103
Description
Bookkeeper currently displays dates in datepicker, tooltips, table columns, and graph period-keys using the YYYY-MM-DD format (e.g., 2025-05-06). While this format works well for internal data processing, it presents several usability challenges in the UI.
Update the display format to DD MMM, YYYY (e.g., 06 May, 2025) due to it's:
- Enhanced Readability
- Reduced International Ambiguity (eliminates MM/DD vs DD/MM confusion)
- Improved UI Consistency