doSend() now parses the JSON error envelope on 401/403/422, distinguishes
the failure modes (Bundle ID mismatch / Token rejected / 422 validation),
and emits a console.warn (once per session, in prod too) that includes:
- the app_id the SDK actually sent
- the masked expected_format returned by the server
- a clear instruction on where to fix it

Resolves the "silent rejection" footgun where a misconfigured project
Bundle ID or stale token would drop crashes without any visible signal in
the host app's console.