actions: enable corepack to use fixed version of yarn

this allows us to fix the version of yarn, the Node.js package manager,
to a particular version. using corepack is the recommended way to use
yarn these days.

.github/workflows/build.yml

@@ -79,6 +79,11 @@ jobs:
           python -m pip install --upgrade pip
           pip install --upgrade platformio setuptools
 
+      - name: Enable Corepack
+        run: |
+            cd webapp
+            corepack enable
+
       - name: Setup Node.js and yarn
         uses: actions/setup-node@v4
         with:
@@ -87,10 +92,14 @@ jobs:
           cache-dependency-path: "webapp/yarn.lock"
 
       - name: Install WebApp dependencies
-        run: yarn --cwd webapp install --frozen-lockfile
+        run: |
+            cd webapp
+            yarn install --frozen-lockfile
 
       - name: Build WebApp
-        run: yarn --cwd webapp build
+        run: |
+            cd webapp
+            yarn build
 
       - name: Build firmware
         run: pio run -e ${{ matrix.environment }}

.github/workflows/yarnlint.yml

@@ -6,8 +6,14 @@ jobs:
   build:
     runs-on: ubuntu-latest
 
+    defaults:
+      run:
+        working-directory: webapp
+
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
+      - name: Enable Corepack
+        run: corepack enable
       - name: Setup Node.js and yarn
         uses: actions/setup-node@v4
         with:
@@ -16,7 +22,7 @@ jobs:
           cache-dependency-path: "webapp/yarn.lock"
 
       - name: Install WebApp dependencies
-        run: yarn --cwd webapp install --frozen-lockfile
+        run: yarn install --frozen-lockfile
 
       - name: Linting
-        run: yarn --cwd webapp lint
+        run: yarn lint

.github/workflows/yarnprettier.yml

@@ -6,8 +6,14 @@ jobs:
   build:
     runs-on: ubuntu-latest
 
+    defaults:
+      run:
+        working-directory: webapp
+
     steps:
       - uses: actions/checkout@v4
+      - name: Enable Corepack
+        run: corepack enable
       - name: Setup Node.js and yarn
         uses: actions/setup-node@v4
         with:
@@ -16,7 +22,7 @@ jobs:
           cache-dependency-path: "webapp/yarn.lock"
 
       - name: Install WebApp dependencies
-        run: yarn --cwd webapp install --frozen-lockfile
+        run: yarn install --frozen-lockfile
 
       - name: Check Formatting
-        run: yarn --cwd webapp prettier --check src/
+        run: yarn prettier --check src/

webapp/package.json

@@ -46,5 +46,6 @@
     "vite-plugin-compression": "^0.5.1",
     "vite-plugin-css-injected-by-js": "^3.5.1",
     "vue-tsc": "^2.1.6"
-  }
+  },
+  "packageManager": "yarn@1.22.22+sha512.a6b2f7906b721bba3d67d4aff083df04dad64c399707841b7acf00f6b133b7ac24255f2652fa22ae3534329dc6180534e98d17432037ff6fd140556e2bb3137e"
 }