Adopt cooperative Windows harness execution

[drafael]

Summary

• record ADR 0002 choosing cooperative harness terminality instead of packaging the reviewed Windows Job Object executable
• add the ordered implementation and recovery plan, with Pi first and exact unknown-state handling
• remove the artifact-producing Windows helper workflow and mark the retained native source for later ordered removal
• align architecture, adapter, recovery, and implementation-status documentation with the approved boundary

Validation

• npm run typecheck
• npm run lint
• npm run format:check
• npm test — 179 tests, 171 passed, 8 platform skips, 0 failures
• modified Markdown local-link and fence check
• git diff --check
• tracked package inventory contains no .exe or .node
• independent review: OK with one stale-status note, corrected before commit

Scope

This PR changes documentation and removes the manual native artifact-promotion workflow. It does not change runtime behavior or generated runtime files. POSIX supervision remains intact; Windows restart reattachment remains disabled.