- L2 container diagram now shows the Prometheus -> ocr:8000 scrape edge
(plus the previously-undrawn Prometheus -> backend edge for symmetry).
- OBSERVABILITY.md gains a full ocr_* metrics table with labels, units,
and the canonical example queries from issue #652.
- New "Internal-only endpoints" subsection captures the unauthenticated
/metrics caveat and provides the Caddy block snippet for the case
where the service ever gets a host port.
- Explicit note that MetricsPathFilter only quiets uvicorn stdout, and
the OCR metrics must never carry PII or document content.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>