[BUG] shutdown.test.js: Mock connections not properly cleaned up during shutdown

[jeloskaisabel]

Describe the bug

__tests__/server/shutdown.test.js fails with a timeout after 5000 ms because mock connections aren’t removed from server.connections during shutdown.
server.stop() waits until shutdownTimeout expires, and Jest times out.
Mock methods like mockConnState.close() or mockSocket.destroy() don’t emit the real events ('close', 'end') expected by _performGracefulShutdown().

This happens both inside the Dev Container and locally (just running npm install + npm test).

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To Reproduce

npm test -- --runInBand

→ shutdown.test.js times out after 5000 ms.
Same result if tests are run inside the Docker dev container.

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Expected behavior

server.stop() should gracefully close all mock connections and complete before reaching the shutdown timeout, allowing the test to finish normally.

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Console output

FAIL __tests__/server/shutdown.test.js
  ● should rollback transactions during shutdown
    Exceeded timeout of 5000 ms for a test.
Jest did not exit one second after the test run has completed.

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Environment

Component	Version / Info
pg-wire-mock	main (1.1.0)
Node.js	v22.x
OS	Windows 11 / Ubuntu 22.04 / Docker base image
Command	npm test -- --runInBand

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Additional context

• Mock connections persist in server.connections, blocking _performGracefulShutdown().
• Increasing Jest timeout only hides the issue.

Likely fix: mock sockets should emit 'close'/'end' so cleanup runs properly.