feat: add CI/CD pipeline with Docker + Nginx

- Add Gitea Actions workflow for auto-deploy on push to main
- Add Dockerfile (nginx:alpine based, with layer caching)
- Add nginx.conf (gzip, autoindex, static caching)
- Add .dockerignore
- Migrate cache.html → cache/index.html for directory-based routing

.dockerignore

@@ -0,0 +1,4 @@
+.git
+.gitea
+LICENSE
+README.md

.gitea/workflows/deploy.yaml

@@ -0,0 +1,33 @@
+name: Deploy
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  deploy:
+    runs-on: aliyun
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Build Docker Image
+        run: |
+          docker build \
+            --cache-from illustrated-algorithm:latest \
+            -t illustrated-algorithm:latest \
+            .
+
+      - name: Deploy Container
+        run: |
+          docker stop illustrated-algorithm 2>/dev/null || true
+          docker rm illustrated-algorithm 2>/dev/null || true
+          docker run -d \
+            --name illustrated-algorithm \
+            --restart unless-stopped \
+            -p 10000:80 \
+            illustrated-algorithm:latest
+
+      - name: Cleanup Dangling Images
+        run: docker image prune -f

Dockerfile

@@ -0,0 +1,18 @@
+FROM nginx:alpine
+
+# Copy nginx config first (changes less often → cached layer)
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+
+# Copy site content
+COPY . /usr/share/nginx/html/
+
+# Remove non-web files from the image
+RUN rm -rf /usr/share/nginx/html/.git \
+           /usr/share/nginx/html/.gitea \
+           /usr/share/nginx/html/.dockerignore \
+           /usr/share/nginx/html/Dockerfile \
+           /usr/share/nginx/html/LICENSE \
+           /usr/share/nginx/html/README.md
+
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]

nginx.conf

@@ -0,0 +1,29 @@
+server {
+    listen 80;
+    server_name _;
+    root /usr/share/nginx/html;
+    index index.html;
+
+    # Gzip compression
+    gzip on;
+    gzip_types text/plain text/css application/javascript application/json image/svg+xml;
+    gzip_min_length 256;
+
+    # Static assets caching
+    location ~* \.(css|js|png|jpg|jpeg|gif|ico|svg|woff2|ttf)$ {
+        expires 7d;
+        add_header Cache-Control "public, no-transform";
+    }
+
+    # Auto-index at root for listing available pages
+    location / {
+        autoindex on;
+        autoindex_exact_size off;
+        autoindex_localtime on;
+    }
+
+    # Each subdirectory serves its page
+    location ~ ^/([^/]+)/ {
+        try_files $uri $uri/ /$1/index.html;
+    }
+}