拡張機能を起動したときにタイトル未定のファイルが開かれないようにする

[kimurash]

Issue

• Close 拡張機能を起動したときにタイトル未定のファイルが開かれないようにする #219

目的

毎回タイトル未定のファイルが開かれるのはウザイ

やったこと

• ファイルが開かれてるときは何も開かない
• ファイルが開かれていない時「ようこそ」を開く

動作確認

けいすけに直接見せる

[Copilot]

Pull Request Overview

This PR alters the activation workflow so that when no editors are open, the welcome walkthrough is shown instead of an untitled file. Otherwise, existing behavior for revealing or creating the webview panel remains unchanged.

• Replace newUntitledFile with openWalkthrough when no editors are open
• Guard the walkthrough command behind an editor-count check
• Reorder imports in extension.ts

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
open-webview.ts	Conditional launch of welcome walkthrough instead of new file
extension.ts	Alphabetized import statements and grouping of type imports

Comments suppressed due to low confidence (1)

frontend/src/commands/functions/open-webview.ts:9

• Add tests to cover both scenarios: when there are open editors (including untitled) and when there are none, to verify the walkthrough is shown only in the no-editors case.

  if (vscode.window.visibleTextEditors.length === 0) {

[cercil0605]

LGTM