Post-demo hardening: decide ERC-165 support or remove unused mapping

[claude-do]

Track the unused supportedInterfaces mapping in diamond storage.

Expected follow-up:

• Either expose/populate supportsInterface() for relevant interfaces, or remove the unused mapping to avoid misleading reviewers.

Full triage doc: https://github.com/OmniPass-world/clan-world/blob/fix/diamond-init-finalize-guard/docs/reviews/pr468-gpt-5-5-pro-followup.md

Immediate fix PR: #475