修复 OCR libGL.so.1 缺失：安装 libgl1 等系统依赖。

- 新增 deploy/install-ocr-deps.sh，update.sh 自动检查

- install.sh 预装 OpenGL/Mesa 库

backend/app/routers/wrong_questions.py

@@ -113,7 +113,10 @@ def _process_wrong_question(question_id: uuid.UUID):
             db.commit()
         except Exception as exc:
             wq.status = WrongQuestionStatus.failed
-            wq.error_message = _short_error(exc, "OCR 识别失败：")
+            msg = _short_error(exc, "OCR 识别失败：")
+            if "libGL" in str(exc):
+                msg += " 请在服务器执行: sudo bash deploy/install-ocr-deps.sh && systemctl restart grade-archive"
+            wq.error_message = msg
             db.commit()
             return
 

backend/app/services/ocr.py

@@ -1,9 +1,14 @@
 from pathlib import Path
 
+import os
+
 from PIL import Image
 
 from app.core.config import settings
 
+# 无图形界面服务器：避免 OpenCV/Paddle 依赖 X11
+os.environ.setdefault("OPENCV_IO_ENABLE_OPENEXR", "0")
+
 _ocr_engine = None