refactor: cleanup public code and clean psalm baseline

[susnux]

Summary

• Add missing template implements
• Use OCP in public interfaces instead of OC

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[provokateurin]

Cool, just one minor thing you might want to check if you haven't done already.