add shared computer feature

frontend/src/routes/[fam]/+layout.server.ts

@@ -194,6 +194,10 @@ export async function load(event) {
 		pickerFamName: '',
 		pickerChildren: [],
 		deviceChildIds,
-		lockMins
+		lockMins,
+		// Per-device shared-computer flag (cookie mirror of the localStorage
+		// flag the TopNav toggle writes). Server can only hint — the client
+		// re-reads localStorage on hydration.
+		sharedDevice: event.cookies.get('fam_shared_device') === '1'
 	};
 }