v4.0.0

Changelog

• 62ccdac Merge pull request #9 from tacoda/feat/charter-rebrand
• 61d4cf1 docs(governance): add GOVERNANCE.md + 4.0 amendment ADR (F3)
• e225173 feat(charter)!: signals + retire the hook kind
• 3f209a0 feat(charter): CHARTER.md entrypoint + thin host pointers
• f7c553c feat(charter): conformance rubric (F4)
• 5562d31 feat(charter): keystone charter coverage — uncharted territory report
• 256e33a feat(charter): keystone charter show [--effective]
• e71ee88 feat(charter): keystone explain + git change flag; MCP explain tool
• aba829f feat(charter,web,mcp): full-featured signals + coverage surfaces
• 0420c4f feat(migrations): add v4.0 — rename .harness/ → .charter/
• 4a2ecda fix(migrations): v4.0 hook-fold rewrites frontmatter only + repoints id
• e1b198e fix(web,mcp): repair charter routes + SSE topic; drop hook kind
• 0ca2af1 refactor!: migrate dogfood charter .harness/ → .charter/
• 0f4a4ec refactor!: rebrand harness → charter (constraint engineering)