fix(toast): remove shake class before hiding to ensure animationend fires

When dismiss() was called on a persistent+shaking toast, the .shake CSS
rule (declared after .hiding) overrode toast-out animation. If shake had
already finished, no animationend fired and the element was never removed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/js/api.js

@@ -42,6 +42,7 @@ export function showToast(title, { message, level = "error", duration = 4000, sh
 
   const dismiss = () => {
     if (!el.parentNode) return;
+    el.classList.remove("shake");
     el.classList.add("hiding");
     el.addEventListener("animationend", () => el.remove(), { once: true });
   };