perf(ocr): increase batch sizes (detector=4, recognition=8)

5GB free on host during OCR, container at 3.8/8GB. Larger batches
use more memory but process faster on CPU.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -86,8 +86,8 @@ services:
       KRAKEN_MODEL_PATH: /app/models/german_kurrent.mlmodel
       OCR_CONFIDENCE_THRESHOLD: "0.3"
       OCR_CONFIDENCE_THRESHOLD_KURRENT: "0.5"
-      RECOGNITION_BATCH_SIZE: "4"
-      DETECTOR_BATCH_SIZE: "2"
+      RECOGNITION_BATCH_SIZE: "8"
+      DETECTOR_BATCH_SIZE: "4"
     networks:
       - archive-net
     healthcheck: