feat(e2e): add Docker-based E2E test infrastructure

docker/fixture-server/Dockerfile

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+FROM nginx:alpine
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+EXPOSE 80

docker/fixture-server/nginx.conf

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+server {
+    listen 80;
+    server_name localhost;
+    root /usr/share/nginx/html;
+    index all-steps.html;
+    
+    location / {
+        try_files $uri $uri/ =404;
+        add_header Access-Control-Allow-Origin *;
+    }
+    
+    location ~ \.html$ {
+        default_type text/html;
+        add_header Access-Control-Allow-Origin *;
+    }
+}