v2.8.0 清空历史真正物理删除 + 请求超时可配修复慢接口被掐断

1. 清空历史=真正清空（不再只是删行留痕）:
   - 清空前先停止所有运行中测试线程，避免其继续写入孤儿数据
   - DELETE 后重置自增序列(sqlite_sequence)，新测试 ID 从 1 开始
   - WAL checkpoint(TRUNCATE) + VACUUM 物理回收文件空间，数据不可恢复
   - 单条删除删光时同样重置自增序列

2. 慢接口被掐断修复（预处理/首字耗时过长 Read timed out）:
   - 读取超时默认 300s→1800s(30分钟)，连接 60s
   - 「速度测试配置」新增 请求超时(秒) 输入框(默认1800)，测试连接+速度采样共用，按次可调(如3600)
   - 超时错误改为友好提示：等待响应超时(超过N秒未收到数据)，引导调大请求超时，不再裸抛 Read timed out
   - 测试启动日志打印当前超时配置
   - 修复案例: 18008 Qwen3.8-FP8 131072 长上下文预填充被 300s 掐断

tester.py

@@ -77,6 +77,9 @@ class TestRunner(threading.Thread):
                  % (" / ".join(str(x) for x in lengths), max_tokens,
                     " / ".join(str(x) for x in concurrency_levels), n,
                     "开" if warmup else "关", "开" if avoid_cache else "关"))
+        to = self.gen.get("read_timeout") or "默认(1800)"
+        self.log("INFO", "请求超时: 连接 %s s | 等待首字/预处理 %s s（接口慢可在左侧调大）"
+                 % (self.gen.get("connect_timeout") or 60, to))
 
         ratio = self._calibrate()
         self.ratio = ratio
@@ -157,7 +160,9 @@ class TestRunner(threading.Thread):
         """
         from concurrent.futures import ThreadPoolExecutor
 
-        gen_opt = {"max_tokens": max_tokens, "avoid_cache": avoid_cache}
+        gen_opt = {"max_tokens": max_tokens, "avoid_cache": avoid_cache,
+                   "connect_timeout": self.gen.get("connect_timeout"),
+                   "read_timeout": self.gen.get("read_timeout")}
 
         def worker(idx):
             prompt = self._finalize_prompt(base_prompt)  # 每流独立随机前缀，避免共享缓存
@@ -240,7 +245,9 @@ class TestRunner(threading.Thread):
         self.log("INFO", "正在校准 token/字符 比例（发送小探测请求）...")
         try:
             m = lp.call_stream(self.cfg, probe,
-                               {"max_tokens": 8, "avoid_cache": False},
+                               {"max_tokens": 8, "avoid_cache": False,
+                                "connect_timeout": self.gen.get("connect_timeout"),
+                                "read_timeout": self.gen.get("read_timeout")},
                                log=lambda lv, msg: self.log(lv, msg),
                                should_stop=self.should_stop)
             pt = m.get("prompt_tokens") or 0