feat(install): ask for QMD local search models and run the QMD installer

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

scripts/tests/test-install-guards.ps1

@@ -17,6 +17,22 @@ try {
     if (Test-AllManifestsPresent @($installed, $missing)) { throw 'Update guard must fail when any selected destination is not installed.' }
     if (-not (Test-AllManifestsPresent @($installed))) { throw 'Update guard must pass when every selected destination is installed.' }
 
+    # QMD prompt: Auto maps device suitability; No never calls the benchmark.
+    . (Join-Path $root 'scripts/lib/install-options.ps1')
+    $originalIn = [Console]::In
+    try {
+        function Test-QmdDevice { param($RepositoryRoot, $HomePath) return $false }
+        [Console]::SetIn([IO.StringReader]::new("a`n"))
+        if ((Read-SemanticRetrievalOption -Default $false -RepositoryRoot $root -HomePath $work) -ne $false) { throw 'Auto unsuitable must yield false' }
+        function Test-QmdDevice { param($RepositoryRoot, $HomePath) return $true }
+        [Console]::SetIn([IO.StringReader]::new("a`n"))
+        if ((Read-SemanticRetrievalOption -Default $false -RepositoryRoot $root -HomePath $work) -ne $true) { throw 'Auto suitable must yield true' }
+        function Test-QmdDevice { throw 'must not run' }
+        [Console]::SetIn([IO.StringReader]::new("n`n"))
+        if ((Read-SemanticRetrievalOption -Default $true -RepositoryRoot $root -HomePath $work) -ne $false) { throw 'No must yield false' }
+    } finally { [Console]::SetIn($originalIn) }
+    if ((Get-Content -Raw (Join-Path $root 'scripts/lib/install-options.ps1')) -notmatch 'Enable local QMD search models \(Qwen3 embedding, Qwen3 reranker, QMD query expansion\)\? \[') { throw 'prompt text changed' }
+
     if ($Summary) { Write-Output 'Tests: PASS | install guards' } else { Write-Output 'PASS install guards: already-installed and not-installed detection' }
 } finally {
     Remove-Item $work -Recurse -Force -ErrorAction SilentlyContinue