## What changed
- Add `StorageTelemetry` to record operation counts, durations, secure-store outcomes, and file fallback reasons using bounded labels. Emit fallback warnings without credential payloads or error text.
- Add task-local client attribution with explicit propagation across task boundaries.
- Preserve typed keyring error causes through `std::io::Error` and the local secrets backend, classifying supported native failures without parsing error messages.
- Remove service names, account names, value lengths, and error text from keyring trace logs.
## Testing
Add tests for buffered metric emission, fallback outcomes, exclusion of sensitive error contents, client attribution isolation, and typed native error classification.
GitOrigin-RevId: 18e7201566a3b09061a6014fd6bd90eae96e3fc2
