- Write each SSE chunk directly to c.Writer and flush immediately
- Remove buffered writer and ticker-based flushing that caused delayed output
- Add 500ms timeout case for consistency with OpenAI/Gemini handlers
- Clean up unused bufio import
This fixes the 'not streaming' issue where small responses were held
in the buffer until timeout/threshold was reached.
Amp-Thread-ID: https://ampcode.com/threads/T-019b1186-164e-740c-96ab-856f64ee6bee
Co-authored-by: Amp <amp@ampcode.com>