feat: RapidOCR default OCR engine, office-only ocr_engine, drop operator toggle

config.yaml

@@ -135,8 +135,8 @@ do:
   max_photos_per_batch: 8
   zone_warn_seconds: 3          # stop soft-warn: recent count activity
   ocr:
-    engine: "tesseract"         # tesseract | paddle | none — YAML seed only
-    # Runtime override: do_settings.json ocr_engine (UI toggle, both ports).
+    engine: "rapid"             # rapid | tesseract | paddle | none — YAML seed only
+    # Runtime override: do_settings.json ocr_engine (office-only write).
 
 output:
   dir: "/opt/jetson-counter"