Add logging for Telegram bot proxy configuration

- Enhanced logging in `Program.cs` to include information about the Telegram bot's proxy settings, improving traceability of network configurations.
- This addition logs the proxy scheme, host, and port, aiding in debugging and monitoring of the bot's connectivity.

backend/src/PnvPanel.Api/Program.cs

@@ -77,6 +77,9 @@ builder.Services.AddSingleton<ITelegramBotClient>(sp =>
         proxy.Credentials = new NetworkCredential(credentials[0], credentials.Length > 1 ? credentials[1] : string.Empty);
     }
 
+    sp.GetRequiredService<ILogger<Program>>().LogInformation(
+        "Telegram bot using proxy {Scheme}://{Host}:{Port}", proxyUri.Scheme, proxyUri.Host, proxyUri.Port);
+
     var handler = new SocketsHttpHandler { Proxy = proxy, UseProxy = true };
     return new TelegramBotClient(token, new HttpClient(handler));
 });