Remove Windows native containment

[drafael]

Summary

• remove the retained Windows Job Object C helper, TypeScript broker/protocol path, build/copy/diagnostic scripts, native documentation, generated declarations, and native-specific tests
• preserve POSIX attempt-scoped process-group supervision and exact restart reattachment
• make built-in Windows CLI adapters explicitly session-scoped/cooperative with restartReattachment: false
• fail closed if a Windows request nevertheless asks for runtime-owned supervision, preventing a direct replacement launch
• add doctor/capability reporting for the native-free Windows boundary
• assert source, generated output, and npm pack contain no project-owned .exe, .node, or runtime native directory
• align architecture, recovery, ADR, implementation status, and validation totals

Validation

• npm run typecheck
• npm run lint
• npm run format:check
• npm test — 187 tests, 185 passed, 2 platform skips, 0 failed
• focused adapter, packaging, and POSIX supervisor tests
• generated dist rebuilt
• changed Markdown links checked
• git diff --check
• filesystem and package inventory contain no project-owned .exe or .node
• independent correctness/security re-review: no issues found

No GitHub or GitLab validation repositories were created.