## Why
Submitting a diagnostic report could appear successful without confirming that Sentry accepted the upload, leaving callers unable to detect transport or HTTP failures.
## What changed
- Send report envelopes through the route-aware HTTP client and await the response.
- Reject redirects, propagate transport and non-success HTTP responses, and include the full error chain in upload JSON-RPC errors.
- Add structured logs for upload attempts, successes, and failures without including report contents.
## Testing
Added coverage for successful uploads, rejected responses, blocked redirects, transport failures, and app-server JSON-RPC error reporting.
GitOrigin-RevId: 07b5cfccd7a65f35d51a720537d2cd8962ed6cdb