Support debug logging of sensitive PII #74

Problem description

While developing the software, certain issues have only been debugable by logging the data read from NFC/OCR. PR #72 introduces such logging, but as stated by Copilot this contradicts our approach of PII handling (see PRIVACY.md).

Suggested solution

Add a toggle to include PII when debug logging is enabled. This should result in a clear warning during startup and should in practice never be enabled in production.

This type of approach would enable us to debug in production without exposing PII if needed, while permitting this in pure test/development environments.