feat: Node バージョンを 22 LTS へ移行 (#194)

* feat: Node バージョンを 22 LTS へ移行

* fix: CI を yarn から npm へ移行

* docs: yarn 前提の解説を npm へ移行

* chore: モノレポ運用していないので不要な設定ファイルを削除

.github/workflows/ci.yml

@@ -22,8 +22,8 @@ jobs:
 
       # Runs a single command using the runners shell
       - name: Install
-        run: yarn install
+        run: npm install
 
       # Runs a set of commands using the runners shell
       - name: Test
-        run: yarn test
+        run: npm test

.gitignore

@@ -110,5 +110,3 @@ dist/
 tmp/
 temp/
 
-# End of https://www.gitignore.io/api/node
-package-lock.json

CONTRIBUTING.md

@@ -4,13 +4,13 @@
 
 ```bash
 git clone https://github.com/vivliostyle/vfm.git && cd vfm
-yarn install
-yarn build
-yarn link
+npm install
+npm run build
+npm link
 DEBUG=vfm vfm
 ```
 
-After setup, run `yarn dev` to watch files.
+After setup, run `npm run dev` to watch files.
 
 ## Commit Guide
 
@@ -29,15 +29,15 @@ release-it --preRelease=beta --npm.tag=next
 ### Bump pre-release version
 
 ```bash
-yarn release:pre
+npm run release:pre
 # or
 release-it --preRelease --npm.tag=next
 ```
 
 ### Graduate
 
 ```bash
-yarn release
+npm run release
 # or
 release-it
 ```

README.md

@@ -66,8 +66,6 @@ vivliostyle build book.html -s A4
 
 ```bash
 npm install --save @vivliostyle/vfm
-# or
-yarn add @vivliostyle/vfm
 ```
 
 ```js