chore(sync): bump mem0 to v2.0.18 - #115

Scanned 2 changed files (Dockerfile, openmemory submodule). The Dockerfile change is a single ARG version bump from v2.0.7 to v2.0.18 with no new instructions, network fetches, or lifecycle hooks added. The openmemory change is a standard git submodule commit update. No CI/CD workflow files were modified. No concrete evidence of malicious intent, unexpected lifecycle events, secret exfiltration, obfuscation, encoded payloads, dependency confusion, typosquatting, privilege escalation, credential handling changes, or dangerous eval/exec patterns was found.