Replace deprecated CloseNotify with Request.Context().Done() for better client disconnect detection

[burybell]

This PR updates the Context.Stream function to use Request.Context().Done() instead of the deprecated CloseNotify() method.

Changes:
Replace w.CloseNotify() with c.Request.Context().Done() for client disconnect signal.

Motivation:
CloseNotify is deprecated and unreliable in modern HTTP/2 environments or when the connection passes through certain proxies or gateways.

Request.Context().Done() provides a more robust and standard-compliant way to detect client disconnects.

Impact:
This change improves compatibility and correctness, especially when using HTTP/2 or reverse proxies.

Let me know if you'd prefer backward compatibility logic for older Gin versions or if further changes are needed.

[Copilot]

Pull Request Overview

This PR replaces the deprecated CloseNotify() method with Request.Context().Done() to improve client disconnect detection, especially in HTTP/2 and reverse proxy environments.

• Replaces w.CloseNotify() with c.Request.Context().Done() in the stream handler
• Enhances compatibility and correctness for client disconnect detection

Comments suppressed due to low confidence (1)

context.go:1211

• The switch to using Request.Context().Done() is a solid update over the deprecated CloseNotify(). Please ensure that c.Request is always non-nil and its context properly reflects cancellation in all deployment scenarios.

clientGone := c.Request.Context().Done()