feat: add build info handling and probe endpoint for services

Dockerfile

@@ -2,6 +2,10 @@ FROM python:3.10-slim
 
 ENV PYTHONDONTWRITEBYTECODE=1
 ENV PYTHONUNBUFFERED=1
+ENV PYTHONPATH=/app
+
+ARG BUILD_ID=dev
+ARG BUILD_TIME_UTC=unknown
 
 RUN apt-get update \
     && apt-get install -y --no-install-recommends build-essential git \
@@ -22,6 +26,8 @@ COPY federation_authority /app/federation_authority
 COPY provider /app/provider
 COPY relying_party /app/relying_party
 
+RUN printf '{\"build_id\":\"%s\",\"built_at_utc\":\"%s\",\"image_marker\":\"cie-auth-image\"}\n' \"$BUILD_ID\" \"$BUILD_TIME_UTC\" > /app/__buildinfo__.json
+
 COPY entrypoint.sh /entrypoint.sh
 COPY scripts /app/scripts
 RUN chmod +x /entrypoint.sh