Add Docker deployment for mcwaddams.mcp.website

Multi-stage build: Node 22 for Astro build, Caddy 2 Alpine for
static file serving. Reverse-proxied via caddy-docker-proxy.

Dockerfile

@@ -0,0 +1,21 @@
+# Stage 1: Build the Astro/Starlight site
+FROM node:22-alpine AS build
+
+WORKDIR /app
+
+COPY package.json package-lock.json* ./
+RUN npm ci
+
+COPY . .
+RUN npm run build
+
+# Stage 2: Serve static files with Caddy
+FROM caddy:2-alpine
+
+COPY --from=build /app/dist /srv
+COPY Caddyfile /etc/caddy/Caddyfile
+
+EXPOSE 8080
+
+HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
+    CMD wget -qO- http://127.0.0.1:8080/health || exit 1