feat: indexer con validacion en dos pasadas y CLI con output de errores

Reescribe el indexer con estrategia de dos pasadas:
1. Parsea todos los .md y construye sets de IDs conocidos
2. Valida integridad contra IDs conocidos, inserta solo los validos

El CLI ahora muestra INVALID para errores de validacion y ERROR
para errores de insercion, separando claramente ambos.
Añade test de integracion que verifica que entradas invalidas
se rechazan sin afectar a las validas.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

registry/parser_test.go

@@ -209,6 +209,9 @@ func TestIndexFullCycle(t *testing.T) {
 	if len(result.Errors) != 0 {
 		t.Errorf("unexpected errors: %v", result.Errors)
 	}
+	if len(result.ValidationErrors) != 0 {
+		t.Errorf("unexpected validation errors: %v", result.ValidationErrors)
+	}
 
 	// Verify searchable
 	fns, err := db.SearchFunctions("filter", "", "", "", "")
@@ -236,3 +239,61 @@ func TestIndexFullCycle(t *testing.T) {
 		t.Error("re-index should produce same counts")
 	}
 }
+
+const invalidPipelineMD = `---
+name: bad_pipeline
+kind: pipeline
+lang: go
+domain: core
+version: "1.0.0"
+purity: pure
+description: "Pipeline puro sin uses_functions — debe fallar."
+tags: []
+uses_functions: []
+uses_types: []
+returns: []
+returns_optional: false
+error_type: ""
+imports: []
+tested: false
+tests: []
+test_file_path: ""
+file_path: "functions/pipelines/bad.go"
+---
+`
+
+func TestIndexRejectsInvalid(t *testing.T) {
+	root := t.TempDir()
+
+	// Valid function
+	writeTempFile(t, root, "functions/core/filter_slice.md", functionMD)
+	// Invalid pipeline (pure + empty uses_functions)
+	writeTempFile(t, root, "functions/pipelines/bad.md", invalidPipelineMD)
+	// Valid type
+	writeTempFile(t, root, "types/finance/ohlcv.md", typeMD)
+
+	dbPath := filepath.Join(root, "registry.db")
+	db, err := Open(dbPath)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	result, err := Index(db, root)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Valid entries should be indexed
+	if result.Functions != 1 {
+		t.Errorf("functions: got %d, want 1 (only the valid one)", result.Functions)
+	}
+	if result.Types != 1 {
+		t.Errorf("types: got %d, want 1", result.Types)
+	}
+
+	// Invalid pipeline should produce validation error
+	if len(result.ValidationErrors) == 0 {
+		t.Error("expected validation errors for invalid pipeline")
+	}
+}