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.

Caddyfile

@@ -0,0 +1,24 @@
+:8080 {
+    root * /srv
+    file_server
+
+    handle /health {
+        respond "OK" 200
+    }
+
+    # SPA-style fallback for clean URLs
+    try_files {path} {path}/ {path}.html /index.html
+
+    # Cache static assets aggressively
+    @static path *.css *.js *.svg *.png *.webp *.jpg *.jpeg *.gif *.ico *.woff *.woff2
+    header @static Cache-Control "public, max-age=31536000, immutable"
+
+    # Security headers
+    header {
+        X-Content-Type-Options "nosniff"
+        X-Frame-Options "DENY"
+        Referrer-Policy "strict-origin-when-cross-origin"
+    }
+
+    encode gzip zstd
+}