Authentication check plus signin screen added to frontend

Frontend/patient_manager/lib/Authentication/authCheck.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart';
+import 'package:patient_manager/main.dart';
+import 'package:patient_manager/pages/home.dart';
+import 'package:patient_manager/pages/signin.dart';
+import 'package:supabase_flutter/supabase_flutter.dart';
+
+class AuthCheck extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return StreamBuilder<AuthState>(
+      stream: client.auth.onAuthStateChange.distinct(),
+      builder: (context, snapshot) {
+        if (snapshot.connectionState == ConnectionState.active) {
+          final user = snapshot.data?.session;
+          if (user == null) {
+            // User not authenticated, show login screen
+            return SignIn();
+          } else {
+            // User authenticated, show home screen
+            return Home();
+          }
+        }
+
+        // Connection state not active, show loading indicator
+        return CircularProgressIndicator();
+      },
+    );
+  }
+}