fix: finalize cross-platform runtime tracking and release docs

[TypeThe0ry]

Summary

• retain exact macOS descendant identities across reparenting/new-session transitions and reject PID reuse
• refresh README, current audit, project status, and changelog to the actual preview.112 release and supported Windows/Linux scope
• preserve fail-closed macOS runtime behavior until native LaunchAgent/containment evidence exists

Validation

• cargo fmt --all -- --check
• cargo test -p cyc-worker --lib — 124 passed, 1 ignored
• scripts/Test-VersionConsistency.ps1 — passed
• scripts/test_packaged_worker_probe_contract.py — 6 passed

No new GitHub issue is created. Stable v0.0.1 remains immutable.