feat: add session validation composable

- Created checkSession composable to validate sessionid query parameter
- Automatically redirects to home page when sessionid is missing

app/composables/checkSession.ts

@@ -0,0 +1,7 @@
+export function checkSession() {
+    const sessionid = useRoute().query.sessionid
+    if (!sessionid) {
+        navigateTo('/')
+    }
+    return sessionid
+}