OCR Worker: add check and systemd install scripts.

deploy/ocr-worker/app.py

@@ -112,12 +112,18 @@ def run_ocr_on_bytes(content: bytes) -> dict:
 
 @app.on_event("startup")
 def warmup():
-    buf = __import__("io").BytesIO()
-    Image.new("RGB", (120, 40), color=(255, 255, 255)).save(buf, format="JPEG")
-    try:
-        run_ocr_on_bytes(buf.getvalue())
-    except Exception:
-        pass
+    """延迟预热，不阻塞 HTTP 服务启动。"""
+    import threading
+
+    def _run():
+        buf = __import__("io").BytesIO()
+        Image.new("RGB", (120, 40), color=(255, 255, 255)).save(buf, format="JPEG")
+        try:
+            run_ocr_on_bytes(buf.getvalue())
+        except Exception:
+            pass
+
+    threading.Thread(target=_run, daemon=True, name="ocr-warmup").start()
 
 
 @app.get("/health")