feat(omo-senpi): mirror ulw mutation skills

[realsigridjin]

Summary

• Mirror exactly the eight requested packages/omo-senpi paths into native Senpi.
• Adapt the two copied test entrypoints to Senpi's existing Vitest and Node URL-path conventions.
• Supersedes feat(omo-senpi): mirror ulw mutation skills #608, whose branch unintentionally inherited two unrelated scripts/check-upstream-release* changes.

Validation

• npm run check passes.
• vitest run packages/coding-agent/test/mcp/catalog-cache.test.ts passes (6 tests).
• The copied OMO fixture tests still require the unmirrored OMO plugin/shared-skill tree (6 pass, 7 fixture-dependent failures); native CI does not register this source mirror as a workspace package.

Scope

Exactly eight files under packages/omo-senpi/; no runtime registration is introduced.

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Summary by cubic

Mirrors the ULW loop and mutation skills into packages/omo-senpi, adds a sync and QA harness, and enforces a contract to keep Senpi’s skills in lockstep with OMO, with no runtime registration changes.

• New Features
  • Added skills/ulw-loop and skills/ulw-mutation-test (with workflow docs and references).
  • Added plugin/scripts/sync-skills.mjs to mirror and stage skills for Senpi.
  • Added scripts/qa/ulw-prompts-e2e.mjs for ULW directive prompt E2E checks.
  • Added tests to verify skill frontmatter and sync integrity: src/components/ulw-loop/mutation-skill-contract.test.ts, src/skills-sync.test.ts.
  • Added AGENTS.md with adapter and component overview.

^{Written for commit 8609ba3. Summary will update on new commits.}