refactor: 集中管理配置常量并优化样式一致性

frontend/src/config/api.js

@@ -0,0 +1,25 @@
+/**
+ * API 相关配置
+ * 集中管理 API 超时、分页、防抖等配置
+ */
+
+export const API_CONFIG = {
+  timeout: parseInt(import.meta.env.VITE_API_TIMEOUT, 10) || 30000,
+  
+  baseURL: import.meta.env.VITE_API_BASE_URL || '/api',
+  
+  pagination: {
+    defaultPageSize: 10,
+    maxPageSize: 1000,
+    pageSizeOptions: [10, 20, 30, 50, 100],
+  },
+  
+  debounceDelay: 300,
+  
+  retry: {
+    maxRetries: 3,
+    retryDelay: 1000,
+  },
+};
+
+export default API_CONFIG;

frontend/src/config/theme.js

@@ -89,6 +89,26 @@ export const designTokens = {
     lg: '24px',
     xl: '32px',
   },
+  typography: {
+    xs: '12px',
+    sm: '13px',
+    base: '14px',
+    md: '16px',
+    lg: '18px',
+    xl: '20px',
+    '2xl': '24px',
+    '3xl': '32px',
+    '4xl': '40px',
+  },
+  zIndex: {
+    dropdown: 1000,
+    sticky: 1020,
+    fixed: 1030,
+    modalBackdrop: 1040,
+    modal: 1050,
+    popover: 1060,
+    tooltip: 1070,
+  },
 };
 
 export default designTokens;