fix: address issue #1463

[blakebeckcoding]

Summary

Potential fix #1463. I did not replicate the bug so this is a defensive fix but I am fairly confident that this is a good fix.

• What changed: fluxer_gateway/src/presence/presence.erl, fluxer_gateway/src/presence/presence_session.erl, fluxer_gateway/src/session/session_connection_presence.erl, fluxer_gateway/test/presence_connect_tests.erl
• Why it is correct: My change makes each gateway session verify that it is still registered with the user’s Presence process.
• Risk: Medium

Verification

• Tests run: cd /workspaces/fluxer/fluxer_gateway

  rebar3 as test eunit --module=presence_connect_tests
  rebar3 as test eunit --module=session_connection_presence

  Results:

  • presence_connect_tests: 4 tests, 0 failures
  • session_connection_presence: 14 tests, 0 failures
  • Total: 18 tests, 0 failures
  • The gateway also compiled successfully during that run.

• Manual checks: None

• Screenshots or recordings: Didn't get any

Checklist

• I understand every change in this PR.
• I can explain what it does and why it is correct.
• I disclosed any LLM coding help below.

LLM Disclosure

• None