fix: open native directory picker for new instances

internal/ui/shell_test.go

@@ -115,3 +115,22 @@ func TestShellIgnoresCancelledPathSearchResult(t *testing.T) {
 		t.Fatal("cancelled result overwrote the editor")
 	}
 }
+
+func TestShellAppliesSelectedInstanceDirectory(t *testing.T) {
+	shell := NewShell(material.NewTheme())
+	shell.OnChooseDirectory(func(context.Context) (string, error) {
+		return `C:\profiles\new-instance`, nil
+	}, nil)
+	shell.chooseInstanceDirectory()
+	var result directoryPickResult
+	select {
+	case result = <-shell.directoryResults:
+	case <-time.After(time.Second):
+		t.Fatal("directory picker did not produce a result")
+	}
+	shell.directoryResults <- result
+	shell.consumeDirectoryResults()
+	if got := shell.instanceDir.Text(); got != `C:\profiles\new-instance` {
+		t.Fatalf("instance dir = %q", got)
+	}
+}