Please address the comments from this code review:
## Overall Comments
- Avoid the no-op `if (config.service === services.deeplx) {}` in `checkConfig` by inverting the logic or using a guard clause to make the intent clearer.
- DRY up the default DeepLX API URL by moving it into a single constant/shared config instead of duplicating it in both `option.ts` and `constant.ts`.
- Leverage the new `servicesType.isUseCustomUrl` helper in `Main.vue` to control the DeepLX URL input visibility rather than a dedicated `showDeepLX` computed property.

## Individual Comments

### Comment 1
<location> `entrypoints/service/deeplx.ts:7` </location>
<code_context>
+
+async function deeplx(message: any) {
+    // deeplx 不支持 zh-Hans，需要转换为 zh
+    let targetLang = config.to === 'zh-Hans' ? 'zh' : config.to;
+    let sourceLang = config.from === 'auto' ? 'auto' : config.from;
+    
+    // 判断是否使用代理或自定义URL
</code_context>

<issue_to_address>
Language code conversion for zh-Hans may need to be more robust.

Consider handling other Chinese language variants (e.g., 'zh-CN', 'zh-Hant') to ensure broader compatibility and prevent failures.
</issue_to_address>

<suggested_fix>
<<<<<<< SEARCH
    // deeplx 不支持 zh-Hans，需要转换为 zh
    let targetLang = config.to === 'zh-Hans' ? 'zh' : config.to;
    let sourceLang = config.from === 'auto' ? 'auto' : config.from;
=======
    // deeplx 不支持部分中文变体，需要统一转换为 zh
    function normalizeChineseLang(lang: string): string {
        // 常见中文变体
        const zhVariants = [
            'zh-Hans', 'zh-CN', 'zh-SG', // 简体
            'zh-Hant', 'zh-TW', 'zh-HK', 'zh-MO' // 繁体
        ];
        if (zhVariants.includes(lang)) {
            return 'zh';
        }
        return lang;
    }
    let targetLang = normalizeChineseLang(config.to);
    let sourceLang = config.from === 'auto' ? 'auto' : config.from;
>>>>>>> REPLACE

</suggested_fix>

### Comment 2
<location> `entrypoints/service/deeplx.ts:34` </location>
<code_context>
+    });
+
+    if (resp.ok) {
+        let result = await resp.json();
+        // DeepLX 返回格式通常是 { code: 200, data: "translated text" }
+        if (result.code === 200) {
+            return result.data;
+        } else {
</code_context>

<issue_to_address>
No error handling for invalid JSON responses.

Wrap resp.json() in a try-catch block to handle invalid JSON and provide a clearer error message.
</issue_to_address>

<suggested_fix>
<<<<<<< SEARCH
    if (resp.ok) {
        let result = await resp.json();
        // DeepLX 返回格式通常是 { code: 200, data: "translated text" }
        if (result.code === 200) {
            return result.data;
        } else {
            throw new Error(`DeepLX 翻译失败: ${result.message || '未知错误'}`);
        }
    } else {
        console.log("DeepLX 翻译失败：", resp);
        throw new Error(`DeepLX 翻译失败: ${resp.status} ${resp.statusText} body: ${await resp.text()}`);
    }
}
=======
    if (resp.ok) {
        let result;
        try {
            result = await resp.json();
        } catch (err) {
            throw new Error(`DeepLX 返回了无效的 JSON 响应: ${err instanceof Error ? err.message : String(err)}`);
        }
        // DeepLX 返回格式通常是 { code: 200, data: "translated text" }
        if (result.code === 200) {
            return result.data;
        } else {
            throw new Error(`DeepLX 翻译失败: ${result.message || '未知错误'}`);
        }
    } else {
        console.log("DeepLX 翻译失败：", resp);
        throw new Error(`DeepLX 翻译失败: ${resp.status} ${resp.statusText} body: ${await resp.text()}`);
    }
}
>>>>>>> REPLACE

</suggested_fix>

### Comment 3
<location> `entrypoints/service/deeplx.ts:42` </location>
<code_context>
+            throw new Error(`DeepLX 翻译失败: ${result.message || '未知错误'}`);
+        }
+    } else {
+        console.log("DeepLX 翻译失败：", resp);
+        throw new Error(`DeepLX 翻译失败: ${resp.status} ${resp.statusText} body: ${await resp.text()}`);
+    }
</code_context>

<issue_to_address>
Logging the entire Response object may not be informative.

Instead, log resp.status, resp.statusText, or the response body for clearer debugging information.
</issue_to_address>

<suggested_fix>
<<<<<<< SEARCH
        console.log("DeepLX 翻译失败：", resp);
        throw new Error(`DeepLX 翻译失败: ${resp.status} ${resp.statusText} body: ${await resp.text()}`);
=======
        const errorBody = await resp.text();
        console.log("DeepLX 翻译失败：", `status: ${resp.status}, statusText: ${resp.statusText}, body: ${errorBody}`);
        throw new Error(`DeepLX 翻译失败: ${resp.status} ${resp.statusText} body: ${errorBody}`);
>>>>>>> REPLACE

</suggested_fix>