toast: cap message max-height with scroll; assertive role for danger toasts (P2-38, P3-55)

src/renderer/components/Toast.tsx

@@ -17,7 +17,7 @@ export default function ToastContainer() {
   if (toasts.length === 0) return null
 
   return (
-    <div className="fixed bottom-4 right-4 z-[60] flex flex-col gap-2" aria-live="polite">
+    <div className="fixed bottom-4 right-4 z-[60] flex flex-col gap-2">
       <AnimatePresence>
         {toasts.map((toast) => {
           const cfg = TONE_CONFIG[toast.tone]
@@ -25,6 +25,8 @@ export default function ToastContainer() {
           return (
             <motion.div
               key={toast.id}
+              role={toast.tone === "danger" ? "alert" : "status"}
+              aria-live={toast.tone === "danger" ? "assertive" : "polite"}
               initial={reduced ? { opacity: 0 } : { opacity: 0, y: 12, scale: 0.96 }}
               animate={{ opacity: 1, y: 0, scale: 1 }}
               exit={reduced ? { opacity: 0 } : { opacity: 0, y: -8, scale: 0.96 }}
@@ -32,7 +34,7 @@ export default function ToastContainer() {
               className={`flex w-[320px] items-start gap-2.5 rounded-lg border px-4 py-3 shadow-lg ${cfg.className}`}
             >
               <Icon size={16} weight="fill" className="mt-px shrink-0" />
-              <span className="min-w-0 flex-1 break-words text-[13px] font-medium">
+              <span className="max-h-[6.5rem] min-w-0 flex-1 overflow-y-auto break-words text-[13px] font-medium leading-relaxed">
                 {toast.message}
               </span>
               <button