feat: 优化仪表盘数据展示和用户体验

- 优化实时TPM显示格式，添加智能单位（K/M）
- 折线图tooltip添加token数单位格式化
- API Keys使用趋势图增加USD金额计算和显示
- 实现鼠标悬浮时数据倒序展示，前3名添加🥇🥈🥉标识
- 后端API添加费用计算支持
- 删除测试脚本，保持代码整洁

🤖 Generated with [Claude Code](https://claude.ai/code)

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

scripts/test-realtime-metrics.js

@@ -1,69 +0,0 @@
-const redis = require('../src/models/redis');
-const logger = require('../src/utils/logger');
-
-async function testRealtimeMetrics() {
-  try {
-    // 连接Redis
-    await redis.connect();
-    
-    // 获取当前时间戳
-    const now = new Date();
-    const currentMinute = Math.floor(now.getTime() / 60000);
-    
-    console.log('=== 时间戳测试 ===');
-    console.log('当前时间:', now.toISOString());
-    console.log('当前分钟时间戳:', currentMinute);
-    console.log('');
-    
-    // 检查最近5分钟的键
-    console.log('=== 检查Redis键 ===');
-    const client = redis.getClient();
-    for (let i = 0; i < 5; i++) {
-      const minuteKey = `system:metrics:minute:${currentMinute - i}`;
-      const exists = await client.exists(minuteKey);
-      const data = await client.hgetall(minuteKey);
-      
-      console.log(`键: ${minuteKey}`);
-      console.log(`  存在: ${exists ? '是' : '否'}`);
-      if (exists && data) {
-        console.log(`  数据: requests=${data.requests}, totalTokens=${data.totalTokens}`);
-      }
-      console.log('');
-    }
-    
-    // 调用getRealtimeSystemMetrics
-    console.log('=== 调用 getRealtimeSystemMetrics ===');
-    const metrics = await redis.getRealtimeSystemMetrics();
-    console.log('结果:', JSON.stringify(metrics, null, 2));
-    
-    // 列出所有system:metrics:minute:*键
-    console.log('\n=== 所有系统指标键 ===');
-    const allKeys = await client.keys('system:metrics:minute:*');
-    console.log('找到的键数量:', allKeys.length);
-    if (allKeys.length > 0) {
-      // 排序并显示最新的10个
-      allKeys.sort((a, b) => {
-        const aNum = parseInt(a.split(':').pop());
-        const bNum = parseInt(b.split(':').pop());
-        return bNum - aNum;
-      });
-      
-      console.log('最新的10个键:');
-      for (let i = 0; i < Math.min(10, allKeys.length); i++) {
-        const key = allKeys[i];
-        const timestamp = parseInt(key.split(':').pop());
-        const timeDiff = currentMinute - timestamp;
-        console.log(`  ${key} (${timeDiff}分钟前)`);
-      }
-    }
-    
-  } catch (error) {
-    console.error('测试失败:', error);
-  } finally {
-    await redis.disconnect();
-    process.exit(0);
-  }
-}
-
-// 运行测试
-testRealtimeMetrics();