Add Empty State UI for Dashboard Activity and Leaderboard Sections

[Riddhi0124]

Problem

Currently, dashboard sections like recent activity, progress, or leaderboard may look incomplete or confusing when there is no user data available. New users may not immediately understand why these sections are empty or what action they should take next.

Proposed Solution

Add a clean empty state UI for dashboard sections when no data is available.

The empty state should include:

A friendly message like “No activity yet”
A short explanation
A call-to-action button such as “Start Solving Problems”
Styling consistent with the AlgoForge design system
Why this matters

This improves the first-time user experience and makes the dashboard feel more polished and user-friendly instead of appearing broken or unfinished.

Acceptance Criteria
Empty state appears when no dashboard activity/data exists
Empty state does not show when real data is available
UI matches existing Tailwind/Radix design style
Responsive on mobile and desktop
No breaking changes to existing dashboard functionality

@Rishabhworkspace please assign this issue to me under SSoC26.

[Riddhi0124]

can you add ssoc 26 label also please @Somil450