fix(migration): ensure config directory exists before writing marker

- Create parent directory before checking/writing migration marker
- Prevents runtime error for fresh installations without config directory
- Defensive fix for edge case where ~/.cc-switch/ doesn't exist yet

src-tauri/src/migration.rs

@@ -145,8 +145,12 @@ fn scan_codex_copies() -> Vec<(String, Option<PathBuf>, Option<PathBuf>, Value)>
 }
 
 pub fn migrate_copies_into_config(config: &mut MultiAppConfig) -> Result<bool, String> {
-    // 如果已迁移过则跳过
+    // 如果已迁移过则跳过；若目录不存在则先创建，避免新装用户写入标记时失败
     let marker = get_marker_path();
+    if let Some(parent) = marker.parent() {
+        std::fs::create_dir_all(parent)
+            .map_err(|e| format!("创建迁移标记目录失败: {}", e))?;
+    }
     if marker.exists() {
         return Ok(false);
     }