fix: add warmup OCR call to avoid timeout on first request

PaddleOCR JIT-compiles on the first .ocr() call, which takes minutes
on CPU-only servers. This causes Traefik 504 Gateway Timeout.

Run a dummy OCR during startup so the first real request is fast.
Also simplify Traefik labels on paddleocr-service.

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

docker-compose.coolify.yml

@@ -157,6 +157,8 @@ services:
       FLAGS_use_mkldnn: "0"
     volumes:
       - paddleocr_models:/root/.paddleocr
+    labels:
+      - "traefik.http.services.paddleocr.loadbalancer.server.port=8095"
     deploy:
       resources:
         limits: