feat(usage): add support for access token and user ID in usage scripts

Add optional accessToken and userId fields to usage query scripts,
enabling queries to authenticated endpoints like /api/user/self.

Changes:
- Add accessToken and userId fields to UsageScript type (frontend & backend)
- Extend script engine to support {{accessToken}} and {{userId}} placeholders
- Update NewAPI preset template to use /api/user/self endpoint
- Add UI inputs for access token and user ID in UsageScriptModal
- Pass new parameters through service layer to script executor

This allows users to query usage data from endpoints that require
login credentials, providing more accurate balance information for
services like NewAPI/OneAPI platforms.

src-tauri/src/usage_script.rs

@@ -12,12 +12,22 @@ pub async fn execute_usage_script(
     api_key: &str,
     base_url: &str,
     timeout_secs: u64,
+    access_token: Option<&str>,
+    user_id: Option<&str>,
 ) -> Result<Value, AppError> {
     // 1. 替换变量
-    let replaced = script_code
+    let mut replaced = script_code
         .replace("{{apiKey}}", api_key)
         .replace("{{baseUrl}}", base_url);
 
+    // 替换 accessToken 和 userId
+    if let Some(token) = access_token {
+        replaced = replaced.replace("{{accessToken}}", token);
+    }
+    if let Some(uid) = user_id {
+        replaced = replaced.replace("{{userId}}", uid);
+    }
+
     // 2. 在独立作用域中提取 request 配置（确保 Runtime/Context 在 await 前释放）
     let request_config = {
         let runtime =