Mih File Structure enhancement

Frontend/lib/mih_objects/session_st.dart

@@ -0,0 +1,23 @@
+class SessionST {
+  final String status;
+  final bool exists;
+
+  const SessionST({
+    required this.status,
+    required this.exists,
+  });
+
+  factory SessionST.fromJson(Map<String, dynamic> json) {
+    return switch (json) {
+      {
+        'status': String status,
+        'exists': bool exists,
+      } =>
+        SessionST(
+          status: status,
+          exists: exists,
+        ),
+      _ => throw const FormatException('Failed to load SessionST.'),
+    };
+  }
+}