🎨 refactor: Refactor dashboard statistics cards and charts layout

- Consolidate 8 individual stat cards into 4 grouped cards:
  * Account Data (Current Balance, Historical Consumption)
  * Usage Statistics (Request Count, Statistics Count)
  * Resource Consumption (Statistics Quota, Statistics Tokens)
  * Performance Metrics (Average RPM, Average TPM)

- Add gradient header backgrounds with white text for card titles:
  * Blue gradient for Account Data
  * Green gradient for Usage Statistics
  * Yellow gradient for Resource Consumption
  * Pink gradient for Performance Metrics

- Implement mini trend charts using real API data:
  * Replace mock data with actual time-series data from API
  * Hide x and y axes to show pure trend lines
  * Display trends only for metrics with available historical data
  * Remove trend charts for Current Balance, Historical Consumption, and Request Count

- Merge model analysis charts into single card:
  * Combine "Model Consumption Distribution" and "Model Call Count Ratio"
  * Use responsive grid layout (vertical on mobile, horizontal on desktop)
  * Update card title to "Model Data Analysis"

- Optimize chart configurations:
  * Hide axes, legends, and tooltips for mini trend charts
  * Maintain color consistency between metrics and trend lines
  * Improve performance by processing all trend data in single API call

web/src/i18n/locales/en.json

@@ -1551,5 +1551,10 @@
   "提供基础功能演示，方便用户了解系统特性。": "Provide basic feature demonstrations to help users understand the system features.",
   "适用于为多个用户提供服务的场景": "Suitable for scenarios where multiple users are provided.",
   "适用于个人使用的场景，不需要设置模型价格": "Suitable for personal use, no need to set model price.",
-  "适用于展示系统功能的场景，提供基础功能演示": "Suitable for scenarios where the system functions are displayed, providing basic feature demonstrations."
+  "适用于展示系统功能的场景，提供基础功能演示": "Suitable for scenarios where the system functions are displayed, providing basic feature demonstrations.",
+  "账户数据": "Account Data",
+  "使用统计": "Usage Statistics",
+  "资源消耗": "Resource Consumption",
+  "性能指标": "Performance Indicators",
+  "模型数据分析": "Model Data Analysis"
 }