Fix: Robust shutdown and error handling for large file change batches in docker compose watch

[amyssnippet]

What I did

• Fixed an issue where docker compose up --watch could become unresponsive after a large number of file changes (e.g., after a branch switch).
• Ensured all watcher and sync goroutines and channels are robustly closed on context cancellation or error.
• Added explicit logging for large batches and context cancellation to prevent stuck processes and ensure graceful shutdown on Ctrl-C.

Related issue

This PR addresses an issue where docker compose up --watch could become unresponsive after a large number of file changes (such as after a branch switch), causing logs to stop and Ctrl-C to not exit cleanly. The issue is #13136 . The fix ensures that all watcher and sync goroutines and channels are robustly closed on context cancellation or error, and adds explicit logging for large batches and context cancellation. This prevents the process from getting stuck and ensures graceful shutdown, even after large file change events.

By fixing:

• I improved the shutdown logic in the watcher and sync system, ensuring all goroutines and channels are closed on context cancellation or error.
• I added explicit logging for large file change batches and for context cancellation.
• The patch directly addresses the symptoms described: logs stopping, Ctrl-C not exiting, and the process getting stuck after a large batch of file changes (such as after a branch switch).