aisman

Create universal formatDuration function with configurable granularity

- Added formatDuration() to dashboard/dashboard.js with configurable maxParts parameter
- Supports both (date1, date2, maxParts) and (milliseconds, maxParts) calling conventions
- Supports all time units: years, months, weeks, days, hours, minutes, seconds
- Exported as Dash.formatDuration() for global access throughout the application
- Refactored calcProjectDevDuration() to use the universal function
- Reduced calcProjectDevDuration from 30 lines to 2 lines of code

Session: -59, Step: 2
Issues: #-953