docs: document policy OCR capture, the feature no spec proposed

Policy OCR shipped 2026-08-01 (5e9cb12) and was documented nowhere. It is
not in INSURANCE_FEATURES_SPEC.md because it did not come from that
meeting — it came out of building the utility statement OCR pipeline in
RECEIPT_CAPTURE_SPEC.md §2 and noticing the same shape fits carrier
policy PDFs. A reader had no way to find that lineage.

New docs/POLICY_OCR.md covers it end to end, with weight on the three
things that are not obvious from the statement side:

- **One PDF = one policy.** Statements arrive bundled one customer per
  page, so there a page is a document. A GMX certificate is one policy
  across two pages, so the pages are concatenated and the parser runs
  once per file — which is why `pageNumber` is a file ordinal and
  `storageKey` is the source PDF, not a page image.
- **The GMX certificate carries no premium at all** — it lives on a
  separate recibo PDF. Hence the null-preserving confirm and the
  double-gated ledger write.
- **OcrModule was extracted out of StatementsModule to make this
  possible**, and that was blocking rather than cosmetic.

Cross-referenced from RECEIPT_CAPTURE_SPEC.md §2 (where it came from),
INSURANCE_FEATURES_SPEC.md (which never proposed it, and whose §4 carrier
API it partly overlaps), PLAN.md step 11, README and RESUME.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -43,11 +43,19 @@ API feature modules: `auth`, `users`, `customers`, `policies`, `properties`,
 `billing`, `bank`, `reports`, `notifications`, `renewals`, `mail`, `statements`,
 `policy-ocr`, `ocr`, `storage`, `settings`, `ops`.
 
-Web routes: `/inicio`, `/clientes`, `/polizas`, `/servicios`, `/estado-cuenta`,
-`/banco` (chequera), `/recibos` (OCR capture), `/notificaciones` (mass email +
+Web routes: `/inicio`, `/clientes`, `/polizas` (+ `/polizas/captura`, policy
+PDF OCR capture), `/servicios`, `/estado-cuenta`, `/banco` (chequera),
+`/recibos` (utility statement OCR capture), `/notificaciones` (mass email +
 renewal avisos; `/renovaciones` is an alias onto its Pólizas tab), `/reportes`,
 `/catalogos`, `/operaciones` (DB ingest/backup, ADMIN), `/usuarios`, `/login`.
 
+Two OCR intakes share one `OcrProvider` seam (`src/ocr/`, Tesseract today):
+utility statements → ledger rows ([`docs/RECEIPT_CAPTURE_SPEC.md`](docs/RECEIPT_CAPTURE_SPEC.md) §2)
+and carrier policy PDFs → `Policy` rows ([`docs/POLICY_OCR.md`](docs/POLICY_OCR.md)).
+Both need `tesseract-ocr`, `tesseract-ocr-data-spa`, `poppler-utils` and object
+storage; each reports its own availability and disables only itself if either
+is missing.
+
 ---
 
 ## Prerequisites