fix(bootstrap): admit rule-heavy Windows hosts within bounded operations

Route elevated retries directly through the serialized helper. Verify and
derive any repair from one pre-write census, retaining fresh ownership
checks and post-write verification. Give NetSecurity operations a bounded
30-second allowance instead of the short probe budget; keep Linux at 3s.

Regress the fifth-window pre-write timeout with a real 3.2-second child
query, retain hung-child termination, and disclose the field failure and
repair in the v0.70.0 notes.

Co-authored by: todlando