Keep response streams alive through connection failures (#37485)

## What changed

- Classify HTTP connection failures separately from other network errors without exposing request URLs.
- For sampling requests, retry connection failures with exponential delays from 5 to 60 seconds and show a `Reconnecting... waiting for network` stream error.
- Preserve the normal stream retry budget while waiting for the provider to become reachable. Keep the existing bounded retry behavior for other retryable errors.

## Testing

- Verify connection errors are classified without leaking URL contents.
- Verify a turn recovers after its provider becomes reachable and still applies the configured retry limit to a subsequent incomplete stream.

GitOrigin-RevId: 646553290c865a1332abd30c4a64ed9266bbfc6f

codex-rs/response-debug-context/src/lib.rs

@@ -65,6 +65,7 @@ pub fn telemetry_transport_error_message(error: &TransportError) -> String {
         TransportError::Http { status, .. } => format!("http {}", status.as_u16()),
         TransportError::RetryLimit => "retry limit reached".to_string(),
         TransportError::Timeout => "timeout".to_string(),
+        TransportError::Connection(err) => err.to_string(),
         TransportError::Network(err) => err.to_string(),
         TransportError::Build(err) => err.to_string(),
     }