[bug] V2.6.4 Openwrt panic on start

### 问题简要描述 / Brief Description

Openwrt 运行版本V2.6.4会PANIC

### 环境信息 / Environment Information

```
2026-06-20T11:07:44.440199679Z ERROR CORE: backtrace saved to easytier-panic.log
panic occurred, if this is a bug, please report this issue on github (https://github.com/easytier/easytier/issues)
easytier version: 2.6.4-8428a89d
os: linux
arch: aarch64
panic is recorded in: easytier-panic.log
thread: main
time: 2026-06-20 11:07:44.440237612 +00:00
location: /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/zstd-safe-7.2.1/src/lib.rs:243:14
panic info: zstd returned null pointer when creating new context
======================================================================
Backtrace []root@CORE-ROUTER-TEN:/tmp# cat easytier-panic.log
root@CORE-ROUTER-TEN:/tmp# free -m
total used free shared buff/cache available
Mem: 231064 138112 51668 3124 41284 74900
Swap: 0 0 0
```

### 节点配置 / Node Configurations

无

### 日志信息 / Log Information

无

### 重现步骤 / Reproduction Steps

无

### 预期结果 / Expected Behavior

_No response_

### 额外信息 / Additional Context

_No response_

Begin with the reported panic location in zstd-safe-7.2.1/src/lib.rs:243:14 and the easytier-panic.log output; verify the failure using EasyTier 2.6.4 on Linux aarch64/OpenWrt. Done means the startup panic is reproduced and the issue has a verified fix or a narrowed, actionable cause.

Written by the indexing model from the issue text.