Clarify qBittorrent status and fix status pill contrast

backend/app/clients/qbittorrent.py

@@ -52,6 +52,17 @@ class QBittorrentClient(ApiClient):
             response = await client.post(f"{self.base_url}{path}", data=data)
             response.raise_for_status()
 
+    async def is_webui_reachable(self) -> bool:
+        if not self.base_url:
+            return False
+        try:
+            async with httpx.AsyncClient(timeout=10.0, follow_redirects=True) as client:
+                response = await client.get(self.base_url)
+                response.raise_for_status()
+            return True
+        except httpx.HTTPError:
+            return False
+
     async def get_torrents(self) -> Optional[Any]:
         return await self._get("/api/v2/torrents/info")