feat(usage): 活跃请求轮询增加缓存与成本字段

- 后端 getActiveRequests 返回新增 cache_creation/read_input_tokens、actual_cost、rate_multiplier
- 前端轮询时同步更新这些字段到记录中
- 优化刷新逻辑：全局刷新开启时停止1秒轮询，关闭时恢复

src/services/usage/service.py

@@ -1713,7 +1713,11 @@ class UsageService:
             Usage.status,
             Usage.input_tokens,
             Usage.output_tokens,
+            Usage.cache_creation_input_tokens,
+            Usage.cache_read_input_tokens,
             Usage.total_cost_usd,
+            Usage.actual_total_cost_usd,
+            Usage.rate_multiplier,
             Usage.response_time_ms,
             Usage.first_byte_time_ms,  # 首字时间 (TTFB)
             Usage.created_at,
@@ -1773,7 +1777,11 @@ class UsageService:
                 "status": "failed" if r.id in timeout_ids else r.status,
                 "input_tokens": r.input_tokens,
                 "output_tokens": r.output_tokens,
+                "cache_creation_input_tokens": r.cache_creation_input_tokens,
+                "cache_read_input_tokens": r.cache_read_input_tokens,
                 "cost": float(r.total_cost_usd) if r.total_cost_usd else 0,
+                "actual_cost": float(r.actual_total_cost_usd) if r.actual_total_cost_usd else None,
+                "rate_multiplier": float(r.rate_multiplier) if r.rate_multiplier else None,
                 "response_time_ms": r.response_time_ms,
                 "first_byte_time_ms": r.first_byte_time_ms,  # 首字时间 (TTFB)
             }