clear ai event prompt after generation

src/app/page.tsx

@@ -164,6 +164,7 @@ export default function HomePage() {
           setEnd(ev.end || '')
           setAllDay(ev.allDay || false)
           setEditingId(null)
+          setAiPrompt("")
           setDialogOpen(true)
           setRecurrenceRule(ev.recurrenceRule || undefined)
         } else {
@@ -179,6 +180,7 @@ export default function HomePage() {
           }
           const stored = await getAllEvents()
           setEvents(stored)
+          setAiPrompt("")
           setSummary(`Added ${data.length} AI-generated events.`)
           setSummaryUpdated(new Date().toLocaleString())
         }
@@ -231,7 +233,7 @@ export default function HomePage() {
       {/* AI Toolbar */}
       {status === "loading" ? <div className='mb-4 p-4 text-center animate-pulse bg-muted'>Loading...</div> : <div>
         {session?.user ? (
-          <div className="flex flex-row gap-4 mb-4 items-start">
+          <div className="flex flex-col sm:flex-row gap-4 mb-4 items-start">
             <div className='w-full'>
               <Textarea
                 className="wrap-anywhere min-h-12"