chore: upgrade Docker base images to Node.js 22 LTS Alpine (v2.7.22)

- Updated all Dockerfiles from node:20-alpine to node:22-alpine
- Addresses known vulnerabilities in older Alpine images
- Provides better long-term support with Node.js 22 LTS (until April 2027)
- Updated documentation to reflect new base image version
- Tested and verified compatibility with all dependencies

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Dockerfile.test

@@ -1,5 +1,5 @@
 # Quick test Dockerfile using pre-built files
-FROM node:20-alpine
+FROM node:22-alpine
 
 WORKDIR /app