Add full app source

Adds the Flutter inventory app source, cleaned up for a shared repo:
generic package name, no hardcoded ERP endpoints (moved to gitignored
local config), no dead auth code, no debug logging of session data.

lib/auth.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/material.dart';
+import 'package:get_storage/get_storage.dart';
+import 'package:inventory_app/views/splash_screen.dart';
+import 'package:inventory_app/my_app.dart';
+import 'package:inventory_app/views/login_view.dart';
+import 'package:inventory_app/service/axelor_client.dart';
+
+class Auth extends StatelessWidget {
+  const Auth({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    final box = GetStorage();
+    String? sessionId = box.read('sessionId');
+
+    if (sessionId == null) {
+      return const LoginView();
+    }
+
+    // Session exists on disk — validate it with the server before granting access
+    return FutureBuilder<bool>(
+      future: AxelorClient.create().then((client) => client.isSessionValid()),
+      builder: (context, snapshot) {
+        if (snapshot.connectionState == ConnectionState.waiting) {
+          return const SplashScreen();
+        } else if (snapshot.hasError || !(snapshot.data ?? false)) {
+          // Session is expired or invalid — clear it and force re-login
+          box.remove('sessionId');
+          box.remove('username');
+          return const LoginView();
+        } else {
+          return MyApp();
+        }
+      },
+    );
+  }
+}