* fix(docker): switch base image to node:22-noble-slim
* docs(adr): add ADR-030 for base image switch
* docs(handoff): add handoff for base image switch
* docs(handoff): set PR number
* docs(handoff): replace PR-NUMBER placeholder with 71
* docs(project-map): update Dockerfile description after base image switch
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Co-authored-by: opencode-agent <agent@opencode.local>
