feat: update backend OCR parser, web app, mobile app camera/preview UI, tests, and documentation with sample images

lib/features/documents/documents_screen.dart

@@ -45,7 +45,8 @@ class _DocumentsScreenState extends ConsumerState<DocumentsScreen> {
           .map((json) => DocumentModel.fromJson(Map<String, dynamic>.from(json)))
           .toList();
 
-      await localStorage.documentBox.clear();
+      // Merge server docs into Hive without clearing first,
+      // so any locally-saved doc (e.g. just confirmed offline) is preserved
       for (var doc in serverDocs) {
         await localStorage.saveDocument(doc);
       }
@@ -184,7 +185,9 @@ class _DocumentsScreenState extends ConsumerState<DocumentsScreen> {
         onTap: () {
           if (doc.status == PendingDocumentStatus.success) {
             context.push('/editor', extra: doc.id).then((_) {
-              _loadDocuments();
+              // Always reload when returning from editor,
+              // whether confirmed or just pressed back
+              if (mounted) _loadDocuments();
             });
           } else if (doc.status == PendingDocumentStatus.error) {
             // Show error options