Merge origin/development into feature/init-command

Development moved the instruction files to .agents/AGENTS.md with symlinks at the root, so this branch's CLAUDE.md edit (the /init paragraph) is ported into .agents/AGENTS.md and the symlink layout is kept. The headless.rs conflict was only a comment both sides' identical signature fix; the comment stays. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>