AGENTS.md Refactor

Goal

Restructure agent instruction files into a small, universal root plus linked, self-contained topic docs.

Guardrails

• Resolve contradictions before reorganizing content.
• Keep root file short (target under ~80 lines).
• Put specifics (language, testing, style) in linked docs, not the root.
• Prefer a hidden folder .agents/ unless the repo already uses another convention.

Workflow (short)