feat(reports): Add "Overdue" as a third category in Reports charts

[ShivaGupta-14]

Is your feature request related to a problem? Please describe.
Currently, the Reports charts only display "Completed" and "Ongoing" tasks. There's no way to distinguish between pending tasks that are on track vs tasks that have passed their due date.

Describe the solution you'd like
Add "Overdue" as a third category in the Reports charts:

• Completed: Tasks with status === 'completed'
• Ongoing: Pending tasks with due date in the future or no due date
• Overdue: Pending tasks with due date in the past

Each chart should display three bars with distinct colors for easy identification.

Describe alternatives you've considered

• Highlight overdue in task list only -> harder to see trends

Additional context
This enhancement builds on top of #322 which fixed the core date parsing and filtering logic in Reports. The parseTaskwarriorDate utility function is already in place to support this feature.

• I want to work on this issue.

[ShivaGupta-14]

@its-me-abhishek once PR #340 is merged, I’ll open a PR for this