fix(theme): improve local search input a11y (#4066)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

src/client/theme-default/components/VPLocalSearchBox.vue

@@ -440,10 +440,20 @@ function formMarkRegex(terms: Set<string>) {
           <input
             ref="searchInput"
             v-model="filterText"
-            :placeholder="buttonText"
-            id="localsearch-input"
+            :aria-activedescendant="selectedIndex > -1 ? ('localsearch-item-' + selectedIndex) : undefined"
+            aria-autocomplete="both"
+            :aria-controls="results?.length ? 'localsearch-list' : undefined"
             aria-labelledby="localsearch-label"
+            autocapitalize="off"
+            autocomplete="off"
+            autocorrect="off"
             class="search-input"
+            id="localsearch-input"
+            enterkeyhint="go"
+            maxlength="64"
+            :placeholder="buttonText"
+            spellcheck="false"
+            type="search"
           />
           <div class="search-actions">
             <button
@@ -482,8 +492,9 @@ function formMarkRegex(terms: Set<string>) {
           <li
             v-for="(p, index) in results"
             :key="p.id"
-            role="option"
+            :id="'localsearch-item-' + index"
             :aria-selected="selectedIndex === index ? 'true' : 'false'"
+            role="option"
           >
             <a
               :href="p.id"