fix(raw): propagate EPIPE after exhausting sendReport retries

[jelmerdehen]

Summary

The retry loop in RawDevice::sendReport:

for (int i = 0; i < max_write_tries && write(_fd, ...) == -1; ++i) {
    auto err = errno;
    if (err != EPIPE)
        throw std::system_error(...);
}

tolerates up to max_write_tries EPIPE returns. If every retry returns EPIPE the loop exits silently and the caller believes the report has been delivered. The HID++ layer then waits for a response that never comes, masking a stuck or disconnected device until io_timeout fires.

Fix

Track the last errno and throw the same std::system_error after the retry budget is spent.

Test plan

• Builds cleanly.
• Disconnect a device mid-write and confirm the caller sees EPIPE instead of waiting on io_timeout.