Create dashboard for AzSDK agent skill usage data

Part of epic #14902.

Build a dashboard to visualize usage data for AzSDK agent skills (invocation counts, user pronmts)

### Goals
- Provide a single place to monitor how AzSDK agent skills are being used by early adopters.
- Make it easy to spot regressions, hot spots, and adoption trends from telemetry.
- Inform prioritization of skill improvements based on real usage signals.

Start by reviewing epic #14902 and the issue's goals for AzSDK agent-skill usage data. Identify the available telemetry and the dashboard entry point before deciding how invocation counts, prompts, regressions, hot spots, and adoption trends should be represented. Done means a usable dashboard provides the requested usage views in one place.

Written by the indexing model from the issue text.