ci: Revise Frontend CI

- Rename build-frontend.yml to frontend-ci.yml
- Add a `pull_request` trigger
- Disable committing and pushing to a `frontend_build_{hash}` branch
- (Re)enable auto-creating a pull request for the new frontend build

.github/workflows/build-frontend.yml

@@ -1,46 +0,0 @@
-name: Build and Commit Frontend
-
-on:
-  push:
-    branches:
-      - master
-      - development
-      - 'ci-test*' # This will match any branch that starts with "ci-test"
-    paths:
-      - 'frontend/**'
-
-jobs:
-  build:
-    permissions:
-      contents: write
-    runs-on: ubuntu-latest
-    steps:
-    - name: Checkout Repo
-      uses: actions/checkout@v4
-    - name: Setup Flutter
-      uses: subosito/flutter-action@v2
-      with:
-        flutter-version: '3.13.2'
-    - name: Build Flutter Web
-      run: |
-        cd frontend
-        flutter build web --base-href /app/
-    - name: Set branch name
-      id: vars
-      run: echo "::set-output name=branch::frontend_build_${GITHUB_SHA}"
-    - name: Commit and Push
-      run: |
-        git config --local user.email "action@github.com"
-        git config --local user.name "GitHub Action"
-        git add frontend/build/web
-        git commit -m "Update frontend build" -a
-        git checkout -b ${{ steps.vars.outputs.branch }}
-        echo "Commit hash: ${GITHUB_SHA}"
-        git push origin ${{ steps.vars.outputs.branch }}
-    # - name: Create Pull Request
-    #   uses: peter-evans/create-pull-request@v3
-    #   with:
-    #     title: "Update frontend build"
-    #     body: "This PR updates the frontend build."
-    #     branch: ${{ steps.vars.outputs.branch }}
-    #     base: "master"

.github/workflows/frontend-ci.yml

@@ -0,0 +1,59 @@
+name: Frontend CI/CD
+
+on:
+  push:
+    branches:
+      - master
+      - development
+      - 'ci-test*' # This will match any branch that starts with "ci-test"
+    paths:
+      - 'frontend/**'
+  pull_request:
+    paths:
+      - 'frontend/**'
+      - '.github/workflows/build-frontend.yml'
+
+jobs:
+  build:
+    permissions:
+      contents: write
+      pull-requests: write
+    runs-on: ubuntu-latest
+    env:
+      BUILD_BRANCH: ${{ format('frontend-build/{0}', github.ref_name) }}
+
+    steps:
+    - name: Checkout Repo
+      uses: actions/checkout@v4
+
+    - name: Setup Flutter
+      uses: subosito/flutter-action@v2
+      with:
+        flutter-version: '3.13.2'
+
+    - name: Build Flutter to Web
+      run: |
+        cd frontend
+        flutter build web --base-href /app/
+
+    # - name: Commit and Push to ${{ env.BUILD_BRANCH }}
+    #   if: github.event_name == 'push'
+    #   run: |
+    #     git config --local user.email "action@github.com"
+    #     git config --local user.name "GitHub Action"
+    #     git add frontend/build/web
+    #     git checkout -B ${{ env.BUILD_BRANCH }}
+    #     git commit -m "Update frontend build to ${GITHUB_SHA:0:7}" -a
+    #     git push -f origin ${{ env.BUILD_BRANCH }}
+
+    - name: Create PR ${{ env.BUILD_BRANCH }} -> ${{ github.ref_name }}
+      if: github.event_name == 'push'
+      uses: peter-evans/create-pull-request@v6
+      with:
+        add-paths: frontend/build/web
+        base: ${{ github.ref_name }}
+        branch: ${{ env.BUILD_BRANCH }}
+        delete-branch: true
+        title: "Update frontend build in `${{ github.ref_name }}`"
+        body: "This PR updates the frontend build based on commit ${{ github.sha }}."
+        commit-message: "Update frontend build based on commit ${{ github.sha }}"