security: Fix ancestry validation to fail safely

- Return false instead of true when ancestry validation fails
- Change warning to error message for clarity
- Prevents potentially incorrect updates when validation is uncertain
- Follows fail-safe principle for security-critical operations

Author: vaind

updater/scripts/cmake-functions.ps1

@@ -83,9 +83,9 @@ function Test-HashAncestry($repo, $oldHash, $newHash) {
         }
     }
     catch {
-        Write-Host "Warning: Could not validate ancestry for $oldHash -> $newHash : $_"
-        # When in doubt, allow the update (safer for automation)
-        return $true
+        Write-Host "Error: Could not validate ancestry for $oldHash -> $newHash : $_"
+        # When in doubt, fail safely to prevent incorrect updates
+        return $false
     }
 }