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/utils.example.dart

@@ -0,0 +1,6 @@
+// Copy this file to utils.dart and fill in your actual endpoints.
+// utils.dart is gitignored so real endpoints never get committed.
+class Utils {
+  static const String url = 'https://your-erp-host.example.com/prod';
+  static const String ticketUrl = 'https://your-ticket-system.example.com/ticket.form.php';
+}