Rollback target per adapt-windows-integration-pr9 design.md.

Contains:
- de695e1: origin/windows-integration HEAD (PR #9)
- 337e5c4: adapt-windows-integration-pr9 proposal (cherry-picked from develop)
- 4c564fc: feat(server): node-guard.ts refuse-to-start on affected Node

MERGE-PLAN §0.1a (revert preload-fastify): no-op — files were never
committed on the PR branch.
MERGE-PLAN §0.2 (detach:false + useWindowsRedirect gate): already
applied by commits 9c497b8 (detach option) and 26e033e (pi-session
detach:false) pre-existing on windows-integration. useWindowsRedirect
branch removed entirely during a73178d platform/ consolidation.