feat: 👷 webpage preview on pull request

+ build artifact caching for optimization

.github/workflows/webpage.yml

@@ -3,7 +3,8 @@ name: Repository webpage
 on:
   push:
     branches: ["main"]
-  workflow_dispatch:
+  pull_request:
+    branches: ["main"]
 
 permissions:
   contents: read
@@ -19,6 +20,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
+      - uses: actions/cache@v4
+        with:
+          path: |
+            vendor/bundle
+            .jekyll-cache
+          key: ${{ runner.os }}-gem-${{ hashFiles('**/Gemfile.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-gem-
       - uses: actions/configure-pages@v5
       - uses: actions/jekyll-build-pages@v1
         with:
@@ -27,6 +36,7 @@ jobs:
       - uses: actions/upload-pages-artifact@v3
 
   deploy:
+    if: ${{ github.event_name != 'pull_request' }}
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}