Add KB lifecycle extension contract

[0thernet]

Outcome

• Adds interview-first KB setup and evolution through explicit proposals.
• Adds a companion-skill contract and inert template with bounded authority.
• Replaces inferred related-to suggestions with Percolation Result V2 and an explicit predicate decision.
• Preserves historical V1 parsing through the 0.18 release line.
• Keeps lifecycle metadata, resolver, and CLI surfaces out of the public package unless the frozen value gate later justifies them.
• Preserves the existing Oh adoption seam and current public-main behavior.

Source evidence

• Exact parent: 836ef3f
• Exact source commit: c7e3000
• Three direct overlaps were resolved current-main-first: README.md, docs/design.md, and skills/kb/SKILL.md.
• Independent semantic, release-surface, and test-contract reviews found no source blocker.
• git diff check is clean.

Draft blockers

• Regenerate and review committed dist output from the combined source tree.
• Run the standalone validation and package-smoke gates.
• Measure the final package and update the active exact file-count and unpacked-byte assertions.
• Resolve the older staged 0.18.0 artifact before staging the final tree. Do not approve staging id 24f8c30d-0bd7-41f4-bf48-cf9c4a391319.

No install, test, build, npm, tag, release, merge, deployment, or provider action was run in this source-only phase.

[0thernet]

Superseded by #25, which recreated the lifecycle and customization work from current main, added the Percolation V2 compatibility repairs, and passed the complete current-head gate.