Research API-first approach with Spring Boot (openapi-generator-maven-plugin) and Vue 3 frontend (openapi-typescript + openapi-fetch). Add T-5 setup task for scaffolding the tooling. Update T-4 to depend on T-5 (removes redundant API client AC), update implementation phases table and mermaid dependency graph. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>