chore: remove tracked build artifacts and add GitHub Pages deployment

- Add .gitignore covering node_modules/, dist/, .DS_Store, editor dirs, and env files
- Untrack node_modules/, dist/, and .DS_Store files that were accidentally committed
- Add .github/workflows/deploy.yml: runs tests, builds with Vite, deploys to GitHub Pages on every push to master

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: QilongTang

.github/workflows/deploy.yml

@@ -0,0 +1,49 @@
+name: Deploy to GitHub Pages
+
+on:
+  push:
+    branches: [master]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: true
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20
+          cache: npm
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
+
+      - name: Build
+        run: npm run build
+
+      - uses: actions/upload-pages-artifact@v3
+        with:
+          path: dist
+
+  deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - id: deployment
+        uses: actions/deploy-pages@v4

.gitignore

@@ -0,0 +1,22 @@
+# Dependencies
+node_modules/
+
+# Build output
+dist/
+
+# macOS
+.DS_Store
+**/.DS_Store
+
+# Editor
+.vscode/
+.idea/
+
+# Env files
+.env
+.env.local
+.env.*.local
+
+# Logs
+*.log
+npm-debug.log*