fix(ci): use version tags instead of pinned SHAs for landing page workflow

The pinned SHA references for actions/deploy-pages and other actions
were not resolving correctly, causing the Deploy job to fail. Switch
to @v4 version tags for all GitHub Actions used in the workflow.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/landing-page.yml

@@ -24,15 +24,15 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v4
+        uses: actions/checkout@v4
 
       - name: Setup pnpm
-        uses: pnpm/action-setup@fe02b34f77f8bc703788d5817da081398fad5dd2 # v4
+        uses: pnpm/action-setup@v4
         with:
           version: 9
 
       - name: Setup Node.js
-        uses: actions/setup-node@1d0ff469b7ec7b3cb9d8673fde0c81c44821de2a # v4
+        uses: actions/setup-node@v4
         with:
           node-version: 22
           cache: pnpm
@@ -53,7 +53,7 @@ jobs:
         run: pnpm run build
 
       - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v3
+        uses: actions/upload-pages-artifact@v3
         with:
           path: Apps/LandingSite/dist
 
@@ -67,4 +67,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac2b3c603fc # v4
+        uses: actions/deploy-pages@v4