Removes the ADR-0020 gate summary, the strict test-suite rule, the
pre-push rehearsal rule, and the commit-authoring rule. Each is already
documented at its owning source: docs/spec/gates.md carries the gate
behaviour and both command invocations, README.md carries the pre-push
rehearsal, and the git plugin's own skills carry commit authoring.
AGENTS.md is meant to hold only what applies to every session, so
content with a canonical home elsewhere does not belong here.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PDj6F7SPXzh3FtPN78dZ88
