fix: handle danger toast case explicitly

[occult]

Summary

Fixes #42

The danger case in useFlashToasts was using JavaScript fallthrough to the error case. While this technically worked, it was confusing and looked like the case was empty/unhandled.

Changes

• Made the danger case explicit with its own toast.error(message) call
• Kept the error case for compatibility

Before

case "danger":
case "error":
  toast.error(message);
  break;

After

case "danger":
  toast.error(message);
  break;
case "error":
  toast.error(message);
  break;

Both approaches work identically, but the explicit version is clearer.