Fall back to HTTP immediately for oversized WebSocket requests (#60840)

## Why

A WebSocket close with code `1009` before any text arrives indicates that the request exceeds the peer's message size limit. Retrying the request over another WebSocket does not address that limit.

## What changed

- Classify these early size rejections as requiring HTTP fallback and switch transports without exhausting WebSocket retries, including during prewarming.
- Preserve ordinary stream retry behavior for size closes after any text frame and for other close codes.

## Testing

Add integration coverage for early size rejections during generation and prewarming, size closes after metadata, rate limits, or response creation, and ordinary closes.

GitOrigin-RevId: 4550d289bb414fec1faae2a195bcc635d394117b

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

@@ -81,6 +81,7 @@ pub fn telemetry_api_error_message(error: &ApiError) -> String {
         ApiError::Transport(transport) => telemetry_transport_error_message(transport),
         ApiError::Api { status, .. } => format!("api error {}", status.as_u16()),
         ApiError::Stream(err) => err.to_string(),
+        ApiError::WebsocketMessageTooLarge => error.to_string(),
         ApiError::ContentFilter => {
             "Incomplete response returned, reason: content_filter".to_string()
         }