feat: 添加调试日志并改进数据库处理逻辑

- 在多个文件中添加调试日志记录功能
- 将数据库连接统一迁移到db_connect.php
- 改进预约时间冲突检测逻辑
- 优化VIP客户数据处理
- 增强套餐查询的健壮性
- 更新预约状态处理流程

update_booking.php

@@ -62,7 +62,16 @@ try {
         }
         
         // 计算新的持续时间（分钟）
-        $duration = $start_dt->diff($end_dt)->i + ($start_dt->diff($end_dt)->h * 60);
+        // #region agent log
+        $log_data = json_encode(['location' => 'update_booking.php:65', 'message' => 'Calculating duration', 'data' => ['start_time' => $new_start_time, 'end_time' => $new_end_time], 'timestamp' => time() * 1000, 'sessionId' => 'debug-session', 'runId' => 'run1', 'hypothesisId' => 'C']);
+        file_put_contents('.cursor/debug.log', $log_data . "\n", FILE_APPEND);
+        // #endregion
+        $interval = $start_dt->diff($end_dt);
+        $duration = ($interval->days * 24 * 60) + ($interval->h * 60) + $interval->i;
+        // #region agent log
+        $log_data = json_encode(['location' => 'update_booking.php:67', 'message' => 'Duration calculated', 'data' => ['duration' => $duration, 'days' => $interval->days, 'hours' => $interval->h, 'minutes' => $interval->i], 'timestamp' => time() * 1000, 'sessionId' => 'debug-session', 'runId' => 'run1', 'hypothesisId' => 'C']);
+        file_put_contents('.cursor/debug.log', $log_data . "\n", FILE_APPEND);
+        // #endregion
         
         // 更新预约时间和持续时间
         $stmt = $pdo->prepare("UPDATE bookings SET start_time = ?, end_time = ?, duration = ?, updated_at = CURRENT_TIMESTAMP WHERE id = ?");