docs: update all-host plugin instructions
docs: add Claude Code plugin section and validation status Documents the local Claude Code plugin package introduced in dango-tech/adlc5#5 (ADLC5 5.0.0) and records what is and is not yet qualified. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
docs: highlight brownfield indexing and retain overview only
docs: add ADLC5 overview to wiki