4822208306
The logMiddleware wrapper (statusWriter) didn't forward Flush, so
`w.(http.Flusher)` in SSE handlers failed and returned the plain text
"streaming unsupported" with 500. SSE clients (agents_dashboard C++ app)
saw a closed connection with no events.
Add Flush() that delegates to the embedded ResponseWriter when it
implements Flusher. Required for /sse/status and /sse/agents/{id}/logs.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>