list() here isn't redundant: _evict() pops from self._connections, so
iterating the dict directly would raise 'changed size during iteration'.
NOSONAR + comment explaining why, per Sonar's own suppression convention
already used in ingestor/app.py.
Only set application_uri when server_uri is configured; otherwise
asyncua's sane default ('urn:freeopcua:client') stood, but the code
explicitly overwrote it with None. Also fixes mypy strict-optional
error caught by the quality gate.
