fix: split HTTP connect/read timeouts (Jellyfin build + qBit stats)

Every HTTP client passed an integer timeout to requests, applying the same
value to BOTH connect and read phases. A slow Jellyfin /Items page or qBit
/sync/maindata blew through the 10s read budget → ReadTimeoutError. Split
into a (connect=5s, read=60s default) tuple via shared http_timeout() helper.
The media index build worker uses a 180s read floor. Existing services with
low timeout_seconds benefit from bumping to 60+.

backend/src/media_library_viewer_api/clients/qbittorrent.py

@@ -12,6 +12,8 @@ from typing import Any
 
 import requests
 
+from media_library_viewer_api.clients.http_timeout import DEFAULT_READ_TIMEOUT, http_timeout
+
 logger = logging.getLogger(__name__)
 
 
@@ -23,7 +25,7 @@ class QbittorrentClient:
     :class:`requests.Session` that carries the login cookie.
     """
 
-    def __init__(self, base_url: str, username: str, password: str, timeout: int = 10) -> None:
+    def __init__(self, base_url: str, username: str, password: str, timeout: float = DEFAULT_READ_TIMEOUT) -> None:
         if not base_url:
             raise ValueError("qBittorrent base_url is required")
         if not username:
@@ -34,7 +36,8 @@ class QbittorrentClient:
             self.base_url += "/api/v2"
         self._username = username
         self._password = password
-        self.timeout = timeout
+        # timeout is the per-response READ timeout (seconds); connect timeout is fixed at 5s.
+        self.timeout = http_timeout(timeout)
         self._session = requests.Session()
         self._logged_in = False