[FEAT] 優化客戶合約管理介面與修復日期偏移問題

1. 整合「客戶詳情」與「合約歷程」至單一側邊欄，改用分頁 (Tabs) 切換介面。
2. 優化清單「服務期程」顯示：根據客戶模式（租賃/買斷）動態顯示對應期間，並使用完整文字標籤取代縮寫。
3. 修復日期 Bug：在 Company 模型指定日期序列化格式為 Y-m-d，解決時區轉換導致的日期減少一天問題。
4. 新增合約歷程資料表模型、遷移檔以及對應的多語系翻譯（中、英、日）。
5. 移除清單操作列中重複的合約歷程圖示。

lang/en.json

@@ -1119,5 +1119,31 @@
     "Model changed to :model": "Model changed to :model",
     "User logged in: :name": "User logged in: :name",
     "Login failed: :account": "Login failed: :account",
-    "Unauthorized login attempt: :account": "Unauthorized login attempt: :account"
+    "Unauthorized login attempt: :account": "Unauthorized login attempt: :account",
+    "Contract Model": "Contract Model",
+    "Warranty Service": "Warranty Service",
+    "Software Service": "Software Service",
+    "Modification History": "Modification History",
+    "No history records": "No history records",
+    "Initial contract registration": "Initial contract registration",
+    "Contract information updated": "Contract information updated",
+    "Warranty Start": "Warranty Start",
+    "Warranty End": "Warranty End",
+    "Software Start": "Software Start",
+    "Software End": "Software End",
+    "Contract History": "Contract History",
+    "Unlimited": "Unlimited",
+    "Change Note": "Change Note",
+    "Log Time": "Log Time",
+    "Service Periods": "Service Periods",
+    "Creator": "Creator",
+    "View Full History": "View Full History",
+    "Contract Start": "Contract Start",
+    "Contract End": "Contract End",
+    "Contract History Detail": "Contract History Detail",
+    "by": "by",
+    "Service Terms": "Service Periods",
+    "Contract": "Contract",
+    "Warranty": "Warranty",
+    "Software": "Software"
 }