fix: use clearActive() method for logout instead of setActive(null)

Changed logout to use the proper clearActive() method from AccountManager instead of setActive(null), which was causing TypeScript type errors. This is the correct way to clear the active account according to the applesauce-accounts API.

src/App.tsx

@@ -27,7 +27,7 @@ function AppRoutes({
   const accountManager = Hooks.useAccountManager()
 
   const handleLogout = () => {
-    accountManager.setActive(null)
+    accountManager.clearActive()
     showToast('Logged out successfully')
   }