Replace deprecated dart:html with package:web

- Updated document_viewer.dart to use web.HTMLIFrameElement/HTMLDivElement
- Updated file_explorer.dart to use web.HTMLAnchorElement for downloads
- Added web and http packages to pubspec.yaml

b0esche_cloud/lib/pages/document_viewer.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'dart:convert';
-import 'dart:html' as html;
+import 'package:web/web.dart' as web;
 import 'dart:ui_web' as ui;
 import '../theme/app_theme.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
@@ -471,7 +471,7 @@ class _DocumentViewerModalState extends State<DocumentViewerModal> {
 
     ui.platformViewRegistry.registerViewFactory(viewType, (int viewId) {
       // Create iframe pointing to the proxy endpoint
-      final iframe = html.IFrameElement()
+      final iframe = web.HTMLIFrameElement()
         ..style.border = 'none'
         ..style.width = '100%'
         ..style.height = '100%'
@@ -487,7 +487,7 @@ class _DocumentViewerModalState extends State<DocumentViewerModal> {
           'allow-same-origin allow-scripts allow-popups allow-popups-to-escape-sandbox allow-forms allow-presentation',
         );
 
-      final container = html.DivElement()
+      final container = web.HTMLDivElement()
         ..style.width = '100%'
         ..style.height = '100%'
         ..style.margin = '0'

b0esche_cloud/lib/pages/file_explorer.dart

@@ -3,7 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:file_picker/file_picker.dart' hide FileType;
 import 'package:path/path.dart' as p;
-import 'dart:html' as html;
+import 'package:web/web.dart' as web;
 import '../blocs/file_browser/file_browser_bloc.dart';
 import '../blocs/file_browser/file_browser_event.dart';
 import '../blocs/file_browser/file_browser_state.dart';
@@ -291,9 +291,10 @@ class _FileExplorerState extends State<FileExplorer> {
       final fullUrl = '${fileService.baseUrl}$downloadUrl';
 
       // Trigger download via anchor element
-      html.AnchorElement(href: fullUrl)
-        ..setAttribute('download', file.name)
-        ..click();
+      final anchor = web.HTMLAnchorElement()
+        ..href = fullUrl
+        ..download = file.name;
+      anchor.click();
 
       if (context.mounted) {
         ScaffoldMessenger.of(

b0esche_cloud/pubspec.lock

@@ -553,7 +553,7 @@ packages:
     source: hosted
     version: "2.0.1"
   http:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: http
       sha256: "87721a4a50b19c7f1d49001e51409bddc46303966ce89a65af4f4e6004896412"
@@ -1422,7 +1422,7 @@ packages:
     source: hosted
     version: "1.2.0"
   web:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: web
       sha256: "868d88a33d8a87b18ffc05f9f030ba328ffefba92d6c127917a2ba740f9cfe4a"

b0esche_cloud/pubspec.yaml

@@ -55,6 +55,8 @@ dependencies:
   infinite_scroll_pagination: ^5.1.1
   collection: ^1.18.0
   syncfusion_flutter_pdfviewer: ^31.1.21
+  web: ^1.1.0
+  http: ^1.2.0
 
 dev_dependencies:
   flutter_test: