Make module-stage LLM handling resilient and report warnings

internal/modules/grammar/module_test.go

@@ -131,6 +131,7 @@ func TestGrammarModuleValidatorChain(t *testing.T) {
 		got = append(got, v.Name())
 	}
 	want := []string{
+		"proposal_shape",
 		"no_effect",
 		"original_text_presence",
 		"confidence_threshold",
@@ -187,7 +188,7 @@ func TestGrammarModuleProposeMapsCorrectionsAndWritesDiagnostics(t *testing.T) {
 	if len(client.calls) != 1 || client.calls[0].StageName != "grammar:proposal" {
 		t.Fatalf("expected one grammar:proposal call, got %+v", client.calls)
 	}
-	if len(out) != 1 || out[0].CorrectedText != "Hello, world" {
+	if len(out.Proposals) != 1 || out.Proposals[0].CorrectedText != "Hello, world" {
 		t.Fatalf("unexpected proposals: %+v", out)
 	}
 	diagFiles, globErr := filepath.Glob(filepath.Join(diagDir, "grammar", "*proposal*response-payload.json"))