Fix GitHub Pages deployment configuration

This commit fixes the 404 error on the documentation site by updating the deployment workflow to use the modern GitHub Pages deployment actions.

Changes:
- Switched from `mkdocs gh-deploy` to building and deploying via GitHub Actions
- Added proper permissions for pages deployment (pages: write, id-token: write)
- Added github-pages environment configuration
- Using actions/configure-pages, actions/upload-pages-artifact, and actions/deploy-pages for deployment

This approach is the recommended way to deploy to GitHub Pages with GitHub Actions.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: GiggleLiu

.github/workflows/docs.yml

@@ -7,10 +7,19 @@ on:
   workflow_dispatch:
 
 permissions:
-  contents: write
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
 
 jobs:
   deploy:
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
@@ -24,5 +33,17 @@ jobs:
         run: |
           pip install mkdocs-material mkdocstrings[python] pymdown-extensions
 
+      - name: Build documentation
+        run: mkdocs build
+
+      - name: Setup Pages
+        uses: actions/configure-pages@v5
+
+      - name: Upload artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: 'site'
+
       - name: Deploy to GitHub Pages
-        run: mkdocs gh-deploy --force
+        id: deployment
+        uses: actions/deploy-pages@v4