Replace KYC_ENCRYPTION_KEY/KYC_ENCRYPTION_KEY_VERSION in .env.example with
the canonical FIELD_ENCRYPTION_KEY/FIELD_ENCRYPTION_KEY_VERSION used by
env-validation.ts and the rotation runbook. Update bootstrap.sh sed line to
substitute the canonical name. Runtime still reads the legacy KYC_* vars as
a deprecated fallback for existing operators.
Co-Authored-By: Paperclip <noreply@paperclip.ing>