Added jwt authenticaation

frontend_splatournament_manager/lib/services/api_client.dart

@@ -0,0 +1,45 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+import 'package:frontend_splatournament_manager/main.dart';
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+class ApiClient {
+  static const String baseUrl = SplatournamentApp.baseUrl;
+  static const _storage = FlutterSecureStorage();
+  
+  static Future<Map<String, String>> _getHeaders() async {
+    final token = await _storage.read(key: 'jwt_token');
+    return {
+      'Content-Type': 'application/json',
+      if (token != null) 'Authorization': 'Bearer $token',
+    };
+  }
+
+  static Future<http.Response> get(String endpoint) async {
+    final headers = await _getHeaders();
+    return await http.get(Uri.parse('$baseUrl$endpoint'), headers: headers);
+  }
+
+  static Future<http.Response> post(String endpoint, Map<String, dynamic> body) async {
+    final headers = await _getHeaders();
+    return await http.post(
+      Uri.parse('$baseUrl$endpoint'),
+      headers: headers,
+      body: jsonEncode(body),
+    );
+  }
+
+  static Future<http.Response> put(String endpoint, Map<String, dynamic> body) async {
+    final headers = await _getHeaders();
+    return await http.put(
+      Uri.parse('$baseUrl$endpoint'),
+      headers: headers,
+      body: jsonEncode(body),
+    );
+  }
+
+  static Future<http.Response> delete(String endpoint) async {
+    final headers = await _getHeaders();
+    return await http.delete(Uri.parse('$baseUrl$endpoint'), headers: headers);
+  }
+}