feat(app): scan-mode sync, confirmation-gated documents, single-pass product classification

Fixes reported from APK field testing: DO/Product scan mode was inconsistent
between the camera drawer and documents screen (now one shared provider,
with an orange/green color cue); unconfirmed scans leaked into history with
placeholder data before the user tapped confirm (backend now gates
GET /documents on a new `confirmed` column, flipped only by PUT); and
Product Scan ran the GPU classifier twice, once at upload and again on
review (now a single pass at upload, persisted and read directly by the
editor). Also removes the unused "Hubungkan ke PO" field and fabricated
PO/SO/DO placeholder values from the Product Scan flow, closes out the
per-document-polling and save-recovery tasks (6.1/6.3), and splits several
touched files to stay under the repo's 256-line guideline.

Full detail in docs/iteration-log.md and backend/docs/iteration-log.md.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

test/product_editor_classification_failure_test.dart

@@ -0,0 +1,52 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:app_pfm_ocr_v2/features/editor/product_editor_screen.dart';
+import 'package:app_pfm_ocr_v2/main.dart';
+import 'package:app_pfm_ocr_v2/core/storage/local_storage.dart';
+import 'package:app_pfm_ocr_v2/models/document_model.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class MockLocalStorage extends LocalStorage {
+  @override
+  Future<void> init() async {}
+  @override
+  List<DocumentModel> getAllDocuments() => [];
+  @override
+  Future<void> savePendingDocument(Map<String, dynamic> data) async {}
+  @override
+  Future<void> removePendingDocument(String id) async {}
+  @override
+  List<Map<String, dynamic>> getAllPendingDocuments() => [];
+}
+
+void main() {
+  testWidgets('shows an explicit retry state instead of fabricated SKU matches when the backend is unreachable', (tester) async {
+    SharedPreferences.setMockInitialValues({});
+
+    final container = ProviderContainer(
+      overrides: [localStorageProvider.overrideWithValue(MockLocalStorage())],
+    );
+    addTearDown(container.dispose);
+
+    await tester.pumpWidget(
+      UncontrolledProviderScope(
+        container: container,
+        child: const MaterialApp(
+          home: ProductEditorScreen(pendingId: null),
+        ),
+      ),
+    );
+
+    await tester.pumpAndSettle(const Duration(seconds: 5));
+
+    // The old behavior fabricated these exact hardcoded matches on any
+    // fetch failure - they must never appear again.
+    expect(find.textContaining('FIESTA SPICY CHICKEN NUGGET'), findsNothing);
+    expect(find.textContaining('AKUMO NUGGET COIN'), findsNothing);
+    expect(find.textContaining('98.5'), findsNothing); // old fake 0.985 confidence
+
+    expect(find.text('Gagal Memuat Klasifikasi Produk'), findsOneWidget);
+    expect(find.widgetWithText(ElevatedButton, 'Coba Lagi'), findsOneWidget);
+  });
+}