fix: resolve channel close panic and improve turbo mode synchronization

- Remove problematic close(turboEOF) call from TurboNetworkWriter.Flush()
  that was causing "close of closed channel" panic when processing multiple files
- Add proper EOF signaling in readFiles() after all files are processed
- Always create new turboEOF channel for each batch to ensure clean state
- Increase flush timeout iterations for turbo mode to handle large file batches
- Add wait time after EOF signal to ensure data transmission completes

This fixes the panic that occurred in TestDCat2 when processing the same
file multiple times, where the TurboNetworkWriter instance was reused
and attempted to close the same channel multiple times.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions