fix(chat): resolve display names from synced contacts (#812)

* test(chat): cover synced contact display names

* feat(chat): resolve names from synced contacts

* fix(chat): use synced names in chat responses

* test(chat): route legacy fallback coverage through resolver

* perf(chat): avoid eager full contact scans

* test(chat): cover adaptive contact lookup strategy

* fix(chat): recognize pre-normalization LID placeholders

* test(chat): cover late LID mapping display names

* fix(chat): close contact lookup block in display-name resolver

* test(chat): silence package logger in LID resolver test

* refactor(chat): resolve display-name client before storage reads

* test(chat): cover client-backed chat name resolution in usecases