feat: add Flutter web build support

apps/service_app/lib/data/services/api_client.dart

@@ -1,7 +1,7 @@
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:http/http.dart' as http;
+import 'package:image_picker/image_picker.dart';
 
 class ApiException implements Exception {
   const ApiException(this.code, this.message);
@@ -38,11 +38,21 @@ class ApiClient {
 
   Future<Object?> put(String path, {Map<String, Object?>? body}) => _send('PUT', path, body: body);
 
-  Future<String> upload(String filePath, {String contentType = 'image/jpeg'}) async {
-    final request = http.MultipartRequest('POST', Uri.parse('$baseUrl/upload/file'));
-    request.headers[HttpHeaders.authorizationHeader] = _tokenProvider();
+  /// 上传跨平台文件对象；浏览器端不能依赖本地文件路径。
+  Future<String> upload(XFile file, {String contentType = 'image/jpeg'}) async {
+    final request = http.MultipartRequest(
+      'POST',
+      Uri.parse('$baseUrl/upload/file'),
+    );
+    request.headers['authorization'] = _tokenProvider();
     request.fields['declared_content_type'] = contentType;
-    request.files.add(await http.MultipartFile.fromPath('file', filePath));
+    request.files.add(
+      http.MultipartFile.fromBytes(
+        'file',
+        await file.readAsBytes(),
+        filename: file.name,
+      ),
+    );
     final response = await http.Response.fromStream(await request.send());
     final details = _decode(response);
     return jsonMap(details)['uri'] as String? ?? '';
@@ -55,15 +65,17 @@ class ApiClient {
     bool authenticated = true,
   }) async {
     final request = http.Request(method, Uri.parse('$baseUrl$path'));
-    request.headers[HttpHeaders.acceptHeader] = 'application/json';
+    request.headers['accept'] = 'application/json';
     if (authenticated && _tokenProvider().isNotEmpty) {
-      request.headers[HttpHeaders.authorizationHeader] = _tokenProvider();
+      request.headers['authorization'] = _tokenProvider();
     }
     if (body != null) {
-      request.headers[HttpHeaders.contentTypeHeader] = 'application/json; charset=UTF-8';
+      request.headers['content-type'] = 'application/json; charset=UTF-8';
       request.body = jsonEncode(body);
     }
-    final response = await http.Response.fromStream(await _client.send(request));
+    final response = await http.Response.fromStream(
+      await _client.send(request),
+    );
     return _decode(response);
   }