Add two new sections to AGENTS.md and CLAUDE.md:
- .memory Files: consult knowledge.md, decisions.md, plans/, research/ at task start
- Instruction File Sync: keep AGENTS.md, CLAUDE.md, .cursorrules, and Copilot CLI instructions in sync when any is updated
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>