Setting up basic API Structure

ac_web/lib/Api/Services/ApiServiceBase.dart

@@ -0,0 +1,24 @@
+import 'package:ac_web/Api/ApiClient.dart';
+
+/// Base class for every service that maps onto one backend controller.
+///
+/// Adding support for a new controller means:
+/// 1. create the dtos under `Api/Dtos`
+/// 2. create a `<Name>Service extends ApiServiceBase` with `controllerRoute`
+/// 3. expose it as a lazy getter on [AcApi]
+abstract class ApiServiceBase {
+  const ApiServiceBase(this.client);
+
+  final ApiClient client;
+
+  /// Route of the controller without leading slash, e.g. `agents`.
+  String get controllerRoute;
+
+  /// Combines the controller route with an optional relative sub path.
+  String route([String? subPath]) {
+    if (subPath == null || subPath.isEmpty) {
+      return controllerRoute;
+    }
+    return '$controllerRoute/$subPath';
+  }
+}