bug(secrets): CLAUDE.md documents wrong API names

## Problem

Current CLAUDE.md references API names that don't match the actual exports:
- Documents `getSecretsManager` — actual export may differ
- Documents `set`/`get`/`delete` methods — actual methods may be `encrypt`/`decrypt`

Needs verification against `packages/secrets/src/` and CLAUDE.md correction.

## Found during

CLAUDE.md audit