[telemetry] Power BI dashboard for feature usage outside provision and deploy

## Problem

Our reporting is provision/deploy shaped. When we ship anything outside that path we have no way to see whether it is being used, whether it works, or whether it is worth continuing to invest in.

## What we'll do

Build a Power BI dashboard for **feature usage outside provision and deploy** — extensions, `env`, `add`, MCP/agent tools, and so on. Per feature:

- Users and invocations
- Success / failure / cancelled
- Success rate
- Error breakdown

`calcAzdExtensionCommands` in `azure-dev-tools` already produces close to this shape and is a good model to follow.

## Done when

Any non-provision/deploy feature can be looked up in the dashboard without writing KQL.