fix: agent finance page styling and cloud data API implementation

- Fix agent finance page: confirmed backend integration is working
- Add agent cloud-variables and cloud-constants API endpoints
- Rewrite agent cloud-data page to use real API calls instead of mock data
- Fix API path: /agent/applications -> /agent/apps
- Remove 'all' value from app filter SelectItem (empty string issue)
- Add cloudData i18n keys for zh and en
- Cloud data is read-only for agents, with CanViewCloudData permission check

frontend/src/plugins/i18n/en.json

@@ -2886,6 +2886,29 @@
         "totalAmount": "Estimated Cost",
         "generateNow": "Generate Now"
       }
+    },
+    "cloudData": {
+      "title": "Cloud Data",
+      "description": "View cloud variables and constants (read-only)",
+      "variables": "Cloud Variables",
+      "constants": "Cloud Constants",
+      "applications": "Applications",
+      "dataList": "Data List",
+      "readOnlyHint": "Read-only mode, data cannot be edited",
+      "allApps": "All Applications",
+      "noVariables": "No cloud variables found",
+      "noConstants": "No cloud constants found",
+      "statusActive": "Active",
+      "statusInactive": "Inactive",
+      "readOnlyNote": "Read-only - Data is for viewing only, no editing allowed",
+      "columns": {
+        "name": "Name",
+        "application": "Application",
+        "scope": "Scope",
+        "value": "Value",
+        "status": "Status",
+        "createdAt": "Created At"
+      }
     }
   },
   "pricing": {

frontend/src/plugins/i18n/zh.json

@@ -2887,6 +2887,29 @@
         "totalAmount": "预计费用",
         "generateNow": "立即生成"
       }
+    },
+    "cloudData": {
+      "title": "云端数据",
+      "description": "查看云端变量和常量数据（只读）",
+      "variables": "云端变量",
+      "constants": "云端常量",
+      "applications": "应用数量",
+      "dataList": "数据列表",
+      "readOnlyHint": "只读模式，数据不可编辑",
+      "allApps": "全部应用",
+      "noVariables": "暂无云端变量数据",
+      "noConstants": "暂无云端常量数据",
+      "statusActive": "启用",
+      "statusInactive": "禁用",
+      "readOnlyNote": "只读模式 - 当前数据仅供查看，无法进行编辑操作",
+      "columns": {
+        "name": "名称",
+        "application": "应用",
+        "scope": "作用域",
+        "value": "值",
+        "status": "状态",
+        "createdAt": "创建时间"
+      }
     }
   },
   "pricing": {