feat: add accessory module card to home page

Add 附件登记 (accessory registration) card to the home page module
registry with developing status, keyboard shortcut 3, and navigation
to AccessoryPage. Refactor _moduleFromShortcut to use dynamic index
lookup for better maintainability.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

lib/pages/home_page.dart

@@ -4,10 +4,11 @@ import 'package:pad_scanner/services/app_config_service.dart';
 import 'package:pad_scanner/pages/settings_page.dart';
 import 'package:pad_scanner/pages/registration_page.dart';
 import 'package:pad_scanner/pages/boxing_page.dart';
+import 'package:pad_scanner/pages/accessory_page.dart';
 import 'package:pad_scanner/services/api_service.dart';
 
 /// Module type enum for each available feature card
-enum ModuleType { registration, boxing, shelfQuery }
+enum ModuleType { registration, boxing, accessory, shelfQuery }
 
 /// Module status for PRD state tracking
 enum ModuleStatus { online, developing, planning }
@@ -64,8 +65,16 @@ class _HomePageState extends State<HomePage> {
       route: '/boxing',
     ),
     FeatureCard(
-      type: ModuleType.shelfQuery,
+      type: ModuleType.accessory,
       shortcut: '3',
+      icon: Icons.build,
+      title: '附件登记',
+      status: ModuleStatus.developing,
+      route: '/accessory',
+    ),
+    FeatureCard(
+      type: ModuleType.shelfQuery,
+      shortcut: '4',
       icon: Icons.search_outlined,
       title: '货架查询',
       status: ModuleStatus.planning,
@@ -101,16 +110,10 @@ class _HomePageState extends State<HomePage> {
 
   FeatureCard? _moduleFromShortcut(KeyEvent event) {
     final shortcut = _shortcutNumberFromKeyEvent(event);
-    if (shortcut == 1) {
-      return _modules[0];
+    if (shortcut == null || shortcut < 1 || shortcut > _modules.length) {
+      return null;
     }
-    if (shortcut == 2) {
-      return _modules[1];
-    }
-    if (shortcut == 3) {
-      return _modules[2];
-    }
-    return null;
+    return _modules[shortcut - 1];
   }
 
   int? _shortcutNumberFromKeyEvent(KeyEvent event) {
@@ -130,6 +133,11 @@ class _HomePageState extends State<HomePage> {
         event.character == '3') {
       return 3;
     }
+    if (key == LogicalKeyboardKey.digit4 ||
+        key == LogicalKeyboardKey.numpad4 ||
+        event.character == '4') {
+      return 4;
+    }
     return null;
   }
 
@@ -181,6 +189,9 @@ class _HomePageState extends State<HomePage> {
       case ModuleType.boxing:
         targetPage = const BoxingPage();
         break;
+      case ModuleType.accessory:
+        targetPage = const AccessoryPage();
+        break;
       case ModuleType.shelfQuery:
         return; // 规划中，不导航
     }