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>

lib/features/documents/documents_tab_switcher.dart

@@ -0,0 +1,82 @@
+import 'package:flutter/material.dart';
+import '../../config/app_config.dart';
+
+class DocumentsTabSwitcher extends StatelessWidget {
+  final String selectedTab;
+  final ValueChanged<String> onTabChanged;
+
+  const DocumentsTabSwitcher({
+    super.key,
+    required this.selectedTab,
+    required this.onTabChanged,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      margin: const EdgeInsets.symmetric(
+        horizontal: AppConfig.spaceLarge,
+        vertical: AppConfig.spaceSmall,
+      ),
+      padding: const EdgeInsets.all(4),
+      decoration: BoxDecoration(
+        color: Colors.grey.shade100,
+        borderRadius: BorderRadius.circular(AppConfig.borderRadiusMedium),
+      ),
+      child: Row(
+        children: [
+          _buildTabItem('DO', 'DO Scan', Icons.description, Icons.description_outlined),
+          _buildTabItem('Product', 'Product Scan', Icons.inventory_2, Icons.inventory_2_outlined),
+        ],
+      ),
+    );
+  }
+
+  Widget _buildTabItem(String value, String label, IconData activeIcon, IconData inactiveIcon) {
+    final isActive = selectedTab == value;
+    // Color cue: DO mode -> doModeColor (orange), Product mode -> primaryColor (green).
+    // Applies to both the icon and the label text (user feedback: "icon dan
+    // juga button turn color sesuai warna statenya") - mirrors the same
+    // icon+color pairing already used in camera_drawer_mode_toggle.dart and
+    // document_card.dart's top-label (task 8.1, docs/api-contract-map.md G11).
+    // Generic/default chrome elsewhere (search icon, print icon, tooltips)
+    // deliberately stays untouched.
+    final activeColor = value == 'DO' ? AppConfig.doModeColor : AppConfig.primaryColor;
+    final color = isActive ? activeColor : AppConfig.textSecondary;
+    return Expanded(
+      child: GestureDetector(
+        onTap: () => onTabChanged(value),
+        child: Container(
+          padding: const EdgeInsets.symmetric(vertical: 8),
+          decoration: BoxDecoration(
+            color: isActive ? Colors.white : Colors.transparent,
+            borderRadius: BorderRadius.circular(AppConfig.borderRadiusSmall),
+            boxShadow: isActive
+                ? [
+                    BoxShadow(
+                      color: Colors.black.withOpacity(0.05),
+                      blurRadius: 4,
+                      offset: const Offset(0, 2),
+                    )
+                  ]
+                : null,
+          ),
+          child: Row(
+            mainAxisAlignment: MainAxisAlignment.center,
+            children: [
+              Icon(isActive ? activeIcon : inactiveIcon, size: 16, color: color),
+              const SizedBox(width: 6),
+              Text(
+                label,
+                style: TextStyle(
+                  fontWeight: isActive ? FontWeight.bold : FontWeight.normal,
+                  color: color,
+                ),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}