fix(utils): decode QR image via np.fromfile for non-ASCII paths

cv2.imread cannot open files under non-ASCII (e.g. Chinese) paths on
Windows, so decode_qrcode_from_path() always returned None when the
project lived under a directory like D:\视频全平台同步\, and the
terminal QR re-print silently failed. Use np.fromfile + cv2.imdecode
instead, which handles arbitrary paths.

utils/login_qrcode.py

@@ -35,7 +35,13 @@ def remove_qrcode_file(qrcode_path: Path | None) -> bool:
 
 
 def decode_qrcode_from_path(qrcode_path: Path) -> str | None:
-    image = cv2.imread(str(qrcode_path))
+    # Windows 下 cv2.imread 不支持中文路径, 改用 np.fromfile + imdecode
+    import numpy as np
+
+    try:
+        image = cv2.imdecode(np.fromfile(str(qrcode_path), dtype=np.uint8), cv2.IMREAD_COLOR)
+    except Exception:
+        return None
     if image is None:
         return None