PHLEGM v8 Checkpoint 20 - Build-architecture validator sync

Compiler log 2026-1007-1904-4566 showed build validation failed before FreeBASIC execution.
Fixed obsolete bootstrap diagnostic sentinel: now checks the active latest-ZIP refusal contract.
Replaced the hardcoded 2026-1006 installer filename with a manifest-derived v<version> search.
Checks both the canonical versioned installer template and its current-version snapshot(s).
Preserved non-destructive CFG clone and no-Python build rules.
Native PowerShell build and FreeBASIC compilation still require user-side verification.
