ci(landing): auto-deploy to CF Pages on push to main

接好 leo 反饋的「Pages auto-deploy 沒接」坑。新增 .github/workflows/deploy-landing.yml：
- push 到 main 且 landing/ 有變動 → build + 部署
- workflow_dispatch 也可手動觸發
- 用既有的 CLOUDFLARE_API_TOKEN / CLOUDFLARE_ACCOUNT_ID secrets
- 用 cloudflare/wrangler-action@v3 標準 action

下次 leo 推 landing 改動就會自動 deploy，不用 wrangler pages deploy 手動跑。

.github/workflows/deploy-landing.yml

@@ -0,0 +1,55 @@
+name: Deploy Landing
+
+# 自動部署 landing/ (Next.js on Cloudflare Pages)
+# 觸發：push 到 main 且 landing/ 有變動，或手動
+# 為何獨立檔：landing 是 Pages 不是 Worker，跟 deploy.yml (掃 wrangler.toml) 邏輯不同
+# Secret 需要：CLOUDFLARE_API_TOKEN, CLOUDFLARE_ACCOUNT_ID（既有）
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'landing/**'
+      - '.github/workflows/deploy-landing.yml'
+  workflow_dispatch:
+
+concurrency:
+  group: deploy-landing-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  deploy:
+    name: Build + Deploy to CF Pages
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      deployments: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: pnpm/action-setup@v4
+        with:
+          version: 10
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+
+      - name: Install
+        working-directory: landing
+        run: pnpm install --no-frozen-lockfile
+
+      - name: Build (Next.js)
+        working-directory: landing
+        run: pnpm next build
+
+      - name: Build for Pages
+        working-directory: landing
+        run: pnpm exec next-on-pages
+
+      - name: Deploy to Cloudflare Pages
+        uses: cloudflare/wrangler-action@v3
+        with:
+          apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN }}
+          accountId: ${{ secrets.CLOUDFLARE_ACCOUNT_ID }}
+          command: pages deploy landing/.vercel/output/static --project-name arcrun-landing --branch main --commit-message "ci ${{ github.sha }}"