Add Firebase hosting preview environment for PRs (#371)

* Add Firebase hosting preview environment for PRs

Add a new GitHub Actions workflow to deploy to Firebase hosting preview environment on PR.

* Create a new workflow file `.github/workflows/deploy-preview.yaml`.
* Set the workflow to trigger on pull requests.
* Use the Firebase hosting deploy action to deploy to the preview environment.
* Configure the PR environment to live for 7 days using the `expires` parameter.
* Update the `uses` action to the correct versions.
* Utilize `yarn` instead of `npm` for installing dependencies and building the project.

---

For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/cohstats/coh2stats?shareId=XXXX-XXXX-XXXX-XXXX).

* Update deploy-preview.yaml

* Update deploy-preview.yaml

* Prettier

Author: petrvecera

.github/workflows/deploy-preview.yaml

@@ -0,0 +1,34 @@
+name: Deploy Preview Environment
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  deploy-preview:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+
+      - name: Install dependencies
+        run: yarn --prefer-offline --frozen-lockfile install
+
+      - name: Build project
+        run: yarn web build
+
+      - name: Deploy to Firebase preview channel
+        uses: FirebaseExtended/action-hosting-deploy@v0
+        with:
+          repoToken: "${{ secrets.GITHUB_TOKEN }}"
+          firebaseServiceAccount: "${{ secrets.FIREBASE_SERVICE_ACCOUNT_COH2_LADDERS_PROD }}"
+          projectId: "coh2-ladders-prod"
+          target: "coh2-ladders-dev"
+          channelId: "pr-${{ github.event.number }}"
+          expires: 7d