CI: Restore the code linting job

Unlike in Serenity, let's just run this job once per PR rather than on
every job. This lets us install fewer dependencies on the build-and-test
pipelines.

.github/actions/setup/action.yml

@@ -29,7 +29,7 @@ runs:
         sudo add-apt-repository ppa:ubuntu-toolchain-r/test
 
         sudo apt-get update
-        sudo apt-get install autoconf autoconf-archive automake ccache clang-18 clang++-18 clang-format-18 lld-18 gcc-13 g++-13 libstdc++-13-dev ninja-build unzip qt6-base-dev qt6-tools-dev-tools libqt6svg6-dev qt6-multimedia-dev libgl1-mesa-dev libpulse-dev libssl-dev libegl1-mesa-dev
+        sudo apt-get install autoconf autoconf-archive automake ccache clang-18 clang++-18 lld-18 gcc-13 g++-13 libstdc++-13-dev ninja-build unzip qt6-base-dev qt6-tools-dev-tools libqt6svg6-dev qt6-multimedia-dev libgl1-mesa-dev libpulse-dev libssl-dev libegl1-mesa-dev
 
         sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-18 100
         sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-18 100
@@ -41,17 +41,12 @@ runs:
         rm ./wabt-1.0.35-ubuntu-20.04.tar.gz
         echo "${{ github.workspace }}/wabt-1.0.35/bin" >> $GITHUB_PATH
 
-    - name: 'Install JS dependencies'
-      if: ${{ inputs.os == 'Linux' }}
-      shell: bash
-      run: sudo npm install -g prettier@2.7.1
-
     - name: 'Install Python dependencies'
       if: ${{ inputs.os == 'Linux' }}
       shell: bash
       run: |
         python3 -m pip install --upgrade pip
-        pip3 install flake8 requests six
+        pip3 install requests six
 
     - name: 'Install Dependencies'
       if: ${{ inputs.os == 'macOS' || inputs.os == 'Android' }}

.github/workflows/lint-code.yml

@@ -0,0 +1,37 @@
+name: Lint Code
+
+on: [ push, pull_request ]
+
+jobs:
+  lint:
+    runs-on: ubuntu-22.04
+    if: always() && github.repository == 'LadybirdBrowser/ladybird'
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set Up Environment
+        shell: bash
+        run: |
+          set -e
+
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+          sudo add-apt-repository 'deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-18 main'
+
+          sudo add-apt-repository ppa:ubuntu-toolchain-r/test
+
+          sudo apt-get update
+          sudo apt-get install clang-format-18 generate-ninja
+
+      - name: Install JS Dependencies
+        shell: bash
+        run: sudo npm install -g prettier@2.7.1
+
+      - name: Install Python Dependencies
+        shell: bash
+        run: |
+          python3 -m pip install --upgrade pip
+          pip3 install flake8
+
+      - name: Lint
+        run: ${{ github.workspace }}/Meta/lint-ci.sh

.github/workflows/lint-commits.yml

@@ -1,4 +1,4 @@
-name: Commit linter
+name: Lint Commit Messages
 
 on: [pull_request_target]
 
@@ -6,7 +6,7 @@ on: [pull_request_target]
 # (… but don't accept overlong 'fixup!' commit descriptions.)
 
 jobs:
-  lint_commits:
+  lint:
     runs-on: ubuntu-22.04
     if: always() && github.repository == 'LadybirdBrowser/ladybird'