Add Dockerfile with nginx for static serving

- Multi-stage build: node:22-alpine builds, nginx:stable-alpine serves
- RFC1918 set_real_ip_from for 10/8, 172.16/12, 192.168/16
- X-Forwarded-For real_ip_header with recursive resolution
- Access log to stdout, error log to stderr (Docker best practice)
- Immutable cache headers for hashed static assets
- SPA fallback via try_files

.dockerignore

@@ -0,0 +1,5 @@
+node_modules
+dist
+.git
+.DS_Store
+*.log