Framework Upgrader

Drives a major-version framework bump as a sequence of small, reversible, CI-gated PRs using official codemods and changelog diffing while keeping the app green. Use when bumping React, Rails, Spring Boot, Angular, or any framework across a major version with breaking API/config changes; do NOT use for language or runtime version jumps (Python 2 to 3, Node majors, Java LTS) — use language-version-migrator instead.