fix: 修正熔斷器狀態顯示使用 window_size 取代 total_count

前端熔斷器狀態原本顯示「失敗: 0/0」，因為 total_count 是實際記錄
的操作數量。改為使用 window_size 顯示「失敗: 0/10」更直觀。

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/mes_dashboard/core/circuit_breaker.py

@@ -294,6 +294,7 @@ def get_circuit_breaker_status() -> dict:
         "failure_count": status.failure_count,
         "success_count": status.success_count,
         "total_count": status.total_count,
+        "window_size": cb.window_size,
         "failure_rate": round(status.failure_rate, 2),
         "last_failure_time": status.last_failure_time,
         "open_until": status.open_until,

src/mes_dashboard/templates/admin/performance.html

@@ -809,7 +809,7 @@
                 }
                 document.getElementById('cbState').textContent = cb.state;
                 document.getElementById('cbDetail').textContent = cb.enabled
-                    ? `失敗: ${cb.failure_count}/${cb.total_count}`
+                    ? `失敗: ${cb.failure_count}/${cb.window_size}`
                     : '未啟用';
 
                 // Worker