feat(website): add responsive homepage and GitHub Pages deployment (#277)

* feat(website): add responsive homepage and Pages deployment

* feat(website): add platform-specific installer download pages

.github/workflows/website.yml

@@ -0,0 +1,86 @@
+name: Website
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - "website/**"
+      - ".github/workflows/website.yml"
+  pull_request:
+    paths:
+      - "website/**"
+      - ".github/workflows/website.yml"
+  workflow_dispatch:
+  release:
+    types: [published]
+  # Releases published by GITHUB_TOKEN do not trigger another release workflow.
+  workflow_run:
+    workflows: [Release]
+    types: [completed]
+
+permissions:
+  contents: read
+
+concurrency:
+  group: website-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build:
+    if: github.event_name != 'workflow_run' || github.event.workflow_run.conclusion == 'success'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pages: read
+    defaults:
+      run:
+        working-directory: website
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+        with:
+          package_json_file: website/package.json
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: pnpm
+          cache-dependency-path: website/pnpm-lock.yaml
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm test
+      - name: Refresh official release downloads
+        env:
+          GITHUB_TOKEN: ${{ github.token }}
+        run: pnpm release:refresh
+      # A PR must be testable before Pages has been enabled in repository settings.
+      - id: pages
+        if: github.event_name != 'pull_request'
+        uses: actions/configure-pages@v5
+      - name: Build static homepage
+        env:
+          BASE_PATH: ${{ github.event_name == 'pull_request' && format('/{0}', github.event.repository.name) || steps.pages.outputs.base_path }}
+          VITE_SITE_URL: ${{ steps.pages.outputs.base_url }}
+        run: pnpm build && pnpm typecheck && pnpm check:static
+      # Also verify a custom-domain / user-site root with no repository prefix.
+      - name: Check root deployment
+        if: github.event_name == 'pull_request'
+        env:
+          BASE_PATH: /
+        run: pnpm build && pnpm check:static
+      - uses: actions/upload-pages-artifact@v4
+        if: github.event_name != 'pull_request'
+        with:
+          path: website/dist/client
+
+  deploy:
+    if: github.ref == 'refs/heads/main' && github.event_name != 'pull_request'
+    needs: build
+    runs-on: ubuntu-latest
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - id: deployment
+        uses: actions/deploy-pages@v4