feat(forms): add isolated Form A iframe adapter

www/.env.example

@@ -5,6 +5,10 @@ PUBLIC_COUNTERS_MOCK_RESULT=success
 PUBLIC_AIA_FORMS_MODE=off
 PUBLIC_AIA_FORMS_LIVE_APPROVED=false
 PUBLIC_AIA_FORMS_MOCK_RESULT=success
+# The real Form A adapter is test-only. All three gates below are required;
+# indexing-enabled builds always fail closed even when they are set.
+PUBLIC_AIA_FORMS_ENVIRONMENT=local
+PUBLIC_AIA_FORMS_ISOLATED_TEST_APPROVED=false
 # Explicit, local-only Form A meeting preview; requires PUBLIC_AIA_FORMS_MODE=mock.
 PUBLIC_AIA_FORM_A_PREVIEW=false
 PUBLIC_ALLOW_INDEXING=false