added guardian login with views for their assigned childs

lib/access/access_requirement.dart

@@ -0,0 +1,15 @@
+import '../session/session.dart';
+
+/// Backend identity a feature needs. Modules and settings sections declare
+/// these; anything whose requirements the session does not meet is hidden.
+enum AccessRequirement {
+  nextcloud;
+
+  bool isMetBy(Session? session) => switch (this) {
+    AccessRequirement.nextcloud => session?.nextcloud != null,
+  };
+}
+
+extension AccessRequirements on Set<AccessRequirement> {
+  bool areMetBy(Session? session) => every((r) => r.isMetBy(session));
+}

lib/access/user_role.dart

@@ -0,0 +1,20 @@
+/// Account role as reported by MarianumConnect. Only used for display and for
+/// deriving policies; features gate on capabilities and requirements instead
+/// of comparing roles.
+enum UserRole {
+  student,
+  teacher,
+  staff,
+  parent,
+  unknown;
+
+  /// Unknown or missing values map to [unknown] so a new server-side role
+  /// never breaks older app versions.
+  static UserRole parse(String? wire) => switch (wire) {
+    'STUDENT' => UserRole.student,
+    'TEACHER' => UserRole.teacher,
+    'STAFF' => UserRole.staff,
+    'PARENT' => UserRole.parent,
+    _ => UserRole.unknown,
+  };
+}