feat: admit Open Exchange Rates

[jasonHzq]

Summary

• admit the verified seven-Endpoint Open Exchange Rates PontxSpec and bilingual product metadata
• bind the public @pontx/open-exchange-rates@0.1.0 registry artifact, source commit, CI, and quality evidence
• remove the resolved candidate/registry-visibility blocker and preserve caller-direct, no-Hub-proxy policy

Verification

• pnpm validate
• pnpm test
• registry fresh install: ESM/CJS imports and pontx-open-exchange-rates CLI list/dry-run

The product Skill is intentionally a separate content-only PR after this admission so its independent-review workflow can run on an eligible scope.