Remove AmfRan from pool on SCTP connection close

[gab-arrobo]

When a RAN connection goroutine exited, the corresponding AmfRan entry was never removed from AMFContext.AmfRanPool. The Dispatch function already handles an empty message as a connection-close signal by calling ran.Remove(), but this signal was never sent on the direct SCTP path.

The fix sends an empty byte slice via handler.HandleMessage in the defer block of handleConnection, reusing the existing empty-message cleanup path. This ensures that on connection close, ran.Remove() is called, which removes all associated RanUe entries, deletes the AmfRan from the pool, and publishes a gNB-disconnected metric event, which prevents stale entries, misdirected paging, and a resource leak proportional to gNB churn.

Also, create a patch release

[Copilot]

Pull request overview

This PR ensures AmfRan entries are removed from AMFContext.AmfRanPool when a direct SCTP RAN connection closes by reusing the existing empty-message cleanup path in ngap.Dispatch.

Changes:

• On SCTP connection goroutine exit, sends an empty message via handler.HandleMessage(conn, []byte{}) to trigger ngap.Dispatch’s len(msg) == 0 close-handling.
• Keeps the cleanup sequence in a single place (ran.Remove()), preventing stale RAN/UE context and leaked pool entries on gNB churn.

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Comments suppressed due to low confidence (1)

VERSION:2

• The VERSION file currently has an extra blank line. Make reads this file via $(shell cat ./VERSION ...), so multiple lines are converted to a space-separated string (e.g. "3.1.2 "), which can lead to invalid/whitespace-tainted tags or labels.

3.1.2

[Copilot]

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Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.