fix(terminal): use pushd for UNC paths in Windows batch launcher

`cmd.exe` cannot set a UNC path (e.g. `\\wsl$\...`) as the current
directory via `cd /d`; it errors with "CMD does not support UNC paths
as current directories". Switch to `pushd` which temporarily maps the
UNC share to a drive letter.

Rename `build_windows_cd_command` → `build_windows_cwd_command` to
reflect the broader semantics. Extract `build_windows_cwd_command_str`
and `is_windows_unc_path` helpers for testability, and add unit tests
covering drive paths, UNC paths, and batch metacharacter escaping.

Also fix minor style issues: sort mod declarations alphabetically,
add missing EOF newline in lightweight.rs, add explicit type annotation
in streaming_responses test, and reformat tray menu builder chain.

src-tauri/src/tray.rs

@@ -393,11 +393,10 @@ pub fn create_tray_menu(
         true,
         crate::lightweight::is_lightweight_mode(),
         None::<&str>,
-    ).map_err(|e| AppError::Message(format!("创建轻量模式菜单失败: {e}")))?;
+    )
+    .map_err(|e| AppError::Message(format!("创建轻量模式菜单失败: {e}")))?;
 
-    menu_builder = menu_builder
-        .item(&lightweight_item)
-        .separator();
+    menu_builder = menu_builder.item(&lightweight_item).separator();
 
     // 退出菜单（分隔符已在上面的 section 循环中添加）
     let quit_item = MenuItem::with_id(app, "quit", tray_texts.quit, true, None::<&str>)
@@ -472,10 +471,8 @@ pub fn handle_tray_menu_event(app: &tauri::AppHandle, event_id: &str) {
                 if let Err(e) = crate::lightweight::exit_lightweight_mode(app) {
                     log::error!("退出轻量模式失败: {e}");
                 }
-            } else {
-                if let Err(e) = crate::lightweight::enter_lightweight_mode(app) {
-                    log::error!("进入轻量模式失败: {e}");
-                }
+            } else if let Err(e) = crate::lightweight::enter_lightweight_mode(app) {
+                log::error!("进入轻量模式失败: {e}");
             }
         }
         "quit" => {