feat: add daily tip & case auto-publish system

- GitHub Actions workflow: daily-content.yml (UTC 00:00 / 北京 08:00)
- Content generation script: .github/scripts/generate-daily.js (Claude API)
- Initial data: website/daily/data.json
- website/index.html: new 每日精选 section with bilingual support

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

.github/workflows/daily-content.yml

@@ -0,0 +1,38 @@
+name: Daily Content Generator
+
+on:
+  schedule:
+    - cron: '0 0 * * *'  # UTC 00:00 = 北京时间 08:00
+  workflow_dispatch:      # 支持手动触发测试
+
+jobs:
+  generate:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Generate daily content
+        env:
+          ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
+        run: node .github/scripts/generate-daily.js
+
+      - name: Commit and push changes
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add website/daily/data.json
+          if git diff --staged --quiet; then
+            echo "No changes to commit"
+          else
+            git commit -m "chore: update daily content $(date -u '+%Y-%m-%d')"
+            git push
+          fi