go_router_builder: TypedRelativeRoute always uses root route

### Steps to reproduce

dependencies

```yaml
environment:
sdk: ^3.9.2
dependencies:
flutter:
sdk: flutter
go_router: ^17.1.0

dev_dependencies:
build_runner: ^2.6.0
go_router_builder: ^4.0.1
```

1. create 3 routes: 2 Typed, 1 Relative
2. add a print statement to go-router redirect: `print("uri=${state.uri});`
3. add the relative route to both other routes
4. add navigation from routeA to routeB eg. `RouteB().push(context)`
5. add navigation from routeA to relativeRoute eg. `RelativeRouteA().pushRelative(context)`
6. add navigation from routeB to relativeRoute eg. `RelativeRouteA().pushRelative(context)`
7. start app
8. navigate from routeA to routeB
9. navigate to relativeRoute
10. notice that the printed uri is `/routeA/relativeRoute` and *not* `/routeB/relativeRoute` as I would expect

### Expected results

I expect to be navigated to /currentRoute/relativeRoute

### Actual results

I get navigated to /rootRoute/relativeRoute

### Code sample

GoRouter
router.dart

```dart
import 'package:go_router/go_router.dart';
import 'package:go_router_sandbox/navigation/app_routes.dart';

abstract class AppRoutes {
static const home = "/home";
static const products = "/products";
static const product = "/products/:id";

// relative routes
static const reviews = "reviews";
}

final router = GoRouter(
initialLocation: AppRoutes.home,
redirect: (context, state) {
print("qqq uri=${state.uri}");
return null;
},
routes: $appRoutes,
);
```

routes.dart

```dart
import 'package:flutter/cupertino.dart';
import 'package:go_router/go_router.dart';
import 'package:go_router_sandbox/screens/home/home_screen.dart';
import 'package:go_router_sandbox/screens/product/product_screen.dart';
import 'package:go_router_sandbox/screens/products_list/products_list_screen.dart';
import 'package:go_router_sandbox/screens/reviews/reviews_list_screen.dart';

import 'app_router.dart';

part 'app_routes.g.dart';

@TypedGoRoute(
path: AppRoutes.home,
routes: [
TypedRelativeGoRoute(path: AppRoutes.reviews),
],
)
class HomeRoute extends GoRouteData with $HomeRoute {
@override
Widget build(BuildContext context, GoRouterState state) {
return HomeScreen();
}
}

@TypedGoRoute(
path: AppRoutes.product,
routes: [
TypedRelativeGoRoute(path: AppRoutes.reviews),
],
)
class ProductRoute extends GoRouteData with $ProductRoute {
final int id;

const ProductRoute(this.id);

@override
Widget build(BuildContext context, GoRouterState state) {
return ProductScreen(id: id);
}
}

@TypedGoRoute(
path: AppRoutes.products,
routes: [
TypedRelativeGoRoute(path: AppRoutes.reviews),
],
)
class ProductsListRoute extends GoRouteData with $ProductsListRoute {
@override
Widget build(BuildContext context, GoRouterState state) {
return ProductsListScreen();
}
}

@TypedRelativeGoRoute(path: AppRoutes.reviews, routes: [])
class ReviewsRoute extends RelativeGoRouteData with $ReviewsRoute {
@override
Widget build(BuildContext context, GoRouterState state) {
return ReviewsListScreen();
}
}
```

Screens
home_screen.dart

```dart
import 'package:flutter/material.dart';
import 'package:go_router_sandbox/navigation/app_routes.dart';

class HomeScreen extends StatelessWidget {
const HomeScreen({super.key});

@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Text("HomeScreen"),
TextButton(
onPressed: () {
ProductsListRoute().push(context);
},
child: Text("Push /products"),
),
TextButton(
onPressed: () {
ReviewsRoute().pushRelative(context);
},
child: Text("Push /home/reviews"),
),
],
),
),
);
}
}
```
product_screens.g.dart

```dart
import 'package:flutter/material.dart';
import 'package:go_router_sandbox/navigation/app_routes.dart';

class ProductScreen extends StatelessWidget {
const ProductScreen({super.key, required this.id});

final int id;

@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Text("PRODUCT :$id"),
TextButton(
onPressed: () {
ReviewsRoute().pushRelative(context);
},
child: Text("Push /products/$id/reviews"),
),
],
),
),
);
}
}
```
products_list.darg
```dart
import 'package:flutter/material.dart';
import '../../navigation/app_routes.dart';

class ProductsListScreen extends StatelessWidget {
const ProductsListScreen({super.key});

@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Text("PRODUCTS"),
...List.generate(10, (i) => i).map((id) {
return TextButton(
onPressed: () {
ProductRoute(id).push(context);
},
child: Text("Product $id"),
);
}),
TextButton(
onPressed: () {
ReviewsRoute().pushRelative(context);
},
child: Text("Push /products/reviews"),
),
],
),
),
);
}
}
```
reviews.dart
```dart
import 'package:flutter/material.dart';

class ReviewsListScreen extends StatelessWidget {
const ReviewsListScreen({super.key});

@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisSize: MainAxisSize.min,
children: [
Text("REVIEWS"),
...List.generate(10, (i) => i).map((id) {
return TextButton(
onPressed: () {},
child: Text("Review $id"),
);
}),
],
),
),
);
}
}
```

### Screenshots or Video

Screenshots / Video demonstration

[Upload media here]

### Logs

Logs

```console
18:03:02.780 I uri=/home
18:03:05.988 I uri=/home/reviews
// back nav

18:03:10.238 I uri=/products
18:03:12.311 I uri=/home/reviews
// back nav

18:03:15.954 I uri=/products/9
18:03:17.020 I uri=/home/reviews

```

### Flutter Doctor output

Doctor output

```console
[✓] Flutter (Channel stable, 3.35.6, on macOS 26.2 25C56 darwin-arm64, locale en-US) [977ms]
• Flutter version 3.35.6 on channel stable at /Users/mth/fvm/versions/3.35.6
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 9f455d2486 (4 months ago), 2025-10-08 14:55:31 -0500
• Engine revision d2913632a4
• Dart version 3.9.2
• DevTools version 2.48.0
• Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-swift-package-manager, enable-lldb-debugging

[✓] Android toolchain - develop for Android devices (Android SDK version 36.1.0) [2.6s]
• Android SDK at /Users/mth/Library/Android/sdk
• Emulator version 36.2.12.0 (build_id 14214601) (CL:N/A)
• Platform android-36, build-tools 36.1.0
• Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
This is the JDK bundled with the latest Android Studio installation on this machine.
To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
• Java version OpenJDK Runtime Environment (build 21.0.8+-14196175-b1038.72)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 26.2) [1,526ms]
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 17C52
• CocoaPods version 1.16.2

[✓] Chrome - develop for the web [6ms]
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2025.2) [6ms]
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 21.0.8+-14196175-b1038.72)

[✓] VS Code (version 1.109.0) [5ms]
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension can be installed from:
🔨 https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Connected device (4 available) [9.5s]
• sdk gphone64 arm64 (mobile) • emulator-5554 • android-arm64 • Android 16 (API 36) (emulator)
• macOS (desktop) • macos • darwin-arm64 • macOS 26.2 25C56 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 144.0.7559.135

[✓] Network resources [608ms]
• All expected network resources are available.

• No issues found!
```