fix(layout): update navigation rail behavior on medium-large breakpoints

- Replace Breakpoints.mediumLarge with Breakpoints.mediumLargeAndUp
- Ensures correct navigation rail behavior for medium-large breakpoints

Author: fulleni

lib/app/view/app_shell.dart

@@ -78,7 +78,7 @@ class AppShell extends StatelessWidget {
         trailingNavRail: Builder(
           builder: (context) {
             final isExtended =
-                Breakpoints.mediumLarge.isActive(context) ||
+                Breakpoints.mediumLargeAndUp.isActive(context) ||
                 Breakpoints.small.isActive(context);
             return Expanded(
               child: Padding(