fix: resolve layout shift in knowledge items with long names (#19832)

Co-authored-by: Tim Baek <tim@openwebui.com>

src/lib/components/layout/Sidebar/SearchInput.svelte

@@ -209,6 +209,7 @@
 			class="w-full rounded-r-xl py-1.5 pl-2.5 text-sm bg-transparent dark:text-gray-300 outline-hidden"
 			placeholder={placeholder ? placeholder : $i18n.t('Search')}
 			autocomplete="off"
+			maxlength="500"
 			bind:value
 			on:input={() => {
 				dispatch('input');