fix: 清理调试代码 + 提升服务稳定性

- 移除 _debug_log、signal handler、atexit 等调试代码
- 添加 allow_reuse_address 防止重启端口占用
- warmup 线程加外层异常捕获防止静默崩溃
- 恢复启动自动打开浏览器

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

monitor_web.py

@@ -1866,6 +1866,7 @@ class Handler(BaseHTTPRequestHandler):
 
 class ThreadedServer(ThreadingMixIn, HTTPServer):
     daemon_threads = True
+    allow_reuse_address = True
 
 
 def main():
@@ -1907,6 +1908,7 @@ def main():
 
     # 后台预热所有 message DB（图片/emoji 解密必需）
     def _warmup():
+        try:
             t0 = time.perf_counter()
             warmup_keys = ["message\\message_resource.db"]
             for i in range(5):
@@ -1920,6 +1922,8 @@ def main():
                     print(f"[warmup] {k} {(time.perf_counter()-t1)*1000:.0f}ms", flush=True)
                 except Exception as e:
                     print(f"[warmup] {k} 失败: {e}", flush=True)
+        except Exception as e:
+            print(f"[warmup] 异常: {e}", flush=True)
         # 构建 emoji 映射（独立解密，不走 cache）
         _build_emoji_lookup(keys)
         print(f"[warmup] 全部完成 {(time.perf_counter()-t0)*1000:.0f}ms", flush=True)
@@ -1934,7 +1938,7 @@ def main():
 
     try:
         os.system(f'cmd.exe /c start http://localhost:{PORT}')
-    except:
+    except Exception:
         pass
 
     try: