fix(line): close response body on successful SendMedia calls

Always route through classifySDKError to ensure resp.Body is
closed even when the API call succeeds.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

pkg/channels/line/line.go

@@ -532,8 +532,8 @@ func (c *LINEChannel) SendMedia(ctx context.Context, msg bus.OutboundMediaMessag
 			To:       msg.ChatID,
 			Messages: []messaging_api.MessageInterface{&textMsg},
 		}, "")
-		if err != nil {
-			return nil, classifySDKError(resp, err)
+		if sdkErr := classifySDKError(resp, err); sdkErr != nil {
+			return nil, sdkErr
 		}
 	}