Build out interactive app functionality for the demo

[scottgerring]

Problem

The web app currently feels limited — it's mostly login, dashboard, and browsing. It's not obvious how to actually interact with the system beyond viewing data. Key actions like awarding/collecting stickers and creating new stickers aren't available through the UI, making the demo less compelling.

Suggested Fix

Build out more interactive functionality to enhance the demo experience. This should include the ability to:

• Assign / collect stickers
• Create new stickers
• Other interactive actions that showcase the full service architecture

This issue is a placeholder for a more detailed breakdown of specific features.

Part of #235