Allow extra IIS bindings when adopting existing site

The installer now requires the expected binding to be present rather
than the only binding, so www and localhost bindings are preserved.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

scripts/install-iis-release.ps1

@@ -200,8 +200,10 @@ function Get-TargetState {
   }
   $bindings = @($site.Bindings.Collection)
   $expectedBinding = Get-BindingInformation
-  if ($bindings.Count -ne 1 -or $bindings[0].protocol -ne 'http' -or $bindings[0].bindingInformation -ne $expectedBinding) {
-    throw "Existing target binding does not exactly match http/$expectedBinding. Refusing adoption or binding changes."
+  # Extra bindings (for example www or localhost) are left untouched; the expected binding must be present.
+  $hasExpectedBinding = @($bindings | Where-Object { $_.protocol -eq 'http' -and $_.bindingInformation -eq $expectedBinding }).Count -gt 0
+  if (-not $hasExpectedBinding) {
+    throw "Existing target does not have the expected binding http/$expectedBinding. Refusing adoption or binding changes."
   }
   $physicalPath = Get-NormalizedPath $site.physicalPath
   $releasesRoot = Join-Path $DeployRoot 'releases'