Epic: CLI telemetry in the backend

Emit a structured event for Flagsmith CLI API usage, route it to Amplitude for retention analysis, and to InfluxDB for volume and error-rate graphs.

### Event

`cli.request.made`, emitted once per authenticated CLI request:

```
cli.version e.g. "2.0.0-beta.3", "dev"
cli.os e.g. "darwin"
cli.arch e.g. "arm64"
organisation.id int, or absent when it cannot be resolved unambiguously
status "success" | "error", from response.status_code >= 400
amplitude.user_id str(request.user.uuid), or absent for a master API key
```

Trace the backend path for authenticated Flagsmith CLI requests first; no file or test entry point is named in the issue. Completion means each request emits one cli.request.made event with the listed fields, derives status from the response, and routes the event to both Amplitude and InfluxDB.

Written by the indexing model from the issue text.