docs(vd960DBN): BLE 日志查询交互过程文档 + 协议 V1.01 动态分包 + 周期心跳

- 新增 docs/DLD960_BLE日志查询交互.md: 0x25/0x26/0x27 完整交互示例
  (真实日志逐字节解析, 分包规则, 第二分包未发问题记录)
- DLD960_BLE协议.md V1.01: 分包上限改为随协商 MTU 动态 (min(MTU-9,94))
- peripheral.c: performPeriodicTask 加 500ms 心跳打印 (确认 TMOS 周期存活
  + resp 队列状态, 定位第二分包为何不续传)

vd960DBN/BLE/OnlyUpdateApp_Peripheral/APP/peripheral.c

@@ -684,6 +684,15 @@ static void peripheralStateNotificationCB(gapRole_States_t newState, gapRoleEven
  */
 static void performPeriodicTask(void)
 {
+    static uint32_t _dbg_cnt = 0;
+    if(++_dbg_cnt >= 10)   /* 500ms heartbeat: confirm TMOS periodic alive */
+    {
+        _dbg_cnt = 0;
+        PRINT("BLE tick: ntf_len=%d ntf_flag=%d resp=%d amt=%d seq=%d off=%d\n",
+               g_notify_buftemp.len, g_notify_buftemp.flag,
+               g_buf_ble_response.flag, g_buf_ble_response.pkg_amount,
+               g_buf_ble_response.pkg_seq, g_buf_ble_response.dat_offset);
+    }
     if(g_flag_notify_temp){
         g_flag_notify_temp = 0;
         peripheralChar4Notify(g_notify_buftemp.buf, g_notify_buftemp.len);