feat(dashboard): creative UX overhaul with storytelling and visual depth #36

Description

The dashboard works but lacks a wow factor. It should tell the story of the prototyping pipeline — not just display data like a template. The UX should speak the app's purpose and be visually attractive.

Acceptance Criteria

• Hero section with compelling headline and animated stat counters
• Pipeline visualization redesigned as a visual funnel or flow with distinct stage colors
• Pie chart for category breakdown (pure CSS/JS, no libraries)
• Status badges with tasteful accent colors (not just monochrome)
• Submission cards expandable to show full details (problem statement, value, demo link)
• Graduation rate displayed as a visual gauge or progress ring
• Subtle accent color palette introduced (restrained, not heavy)
• Smooth micro-interactions where functional (counter animations, card expand)
• Overall design feels purposeful and tells the prototyping story at a glance

Out of Scope

• External JS libraries or frameworks
• Backend or data structure changes