Fix broken Quick Assign dropdown (#102)

quickAssign() wired lt.combobox.init() with an onSelect callback, but
combobox only supports the multi-select onChange(selected[]) contract
— onSelect is never invoked, so _quickAssignUserId stayed undefined no
matter what the user picked and Quick Assign always showed "Please
select a user from the list." Switched to lt.typeahead.init(), which
does support onSelect, matching the already-working Bulk Assign modal.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MGDKHiU5RJdo3dqQUDow3X

assets/js/dashboard.js

@@ -1139,12 +1139,11 @@ function quickAssign(ticketId) {
                 <div class="lt-modal-body">
                     <p class="lt-mb-xs lt-text-muted lt-text-xs">Ticket #${lt.escHtml(String(ticketId))}</p>
                     <label class="lt-label">Assign to:</label>
-                    <div class="lt-combobox" id="quickAssignCombobox">
-                        <div class="lt-combobox-input-wrap">
-                            <input type="text" class="lt-combobox-input" id="quickAssignInput"
-                                   placeholder="Search users…" autocomplete="off" aria-label="Search users">
-                        </div>
-                        <ul class="lt-combobox-list" role="listbox" aria-hidden="true"></ul>
+                    <div class="lt-typeahead" id="quickAssignTypeahead" style="position:relative">
+                        <input type="text" class="lt-input lt-w-full" id="quickAssignInput"
+                               placeholder="Search users…" autocomplete="off" spellcheck="false"
+                               aria-label="Search users" aria-autocomplete="list">
+                        <div class="lt-typeahead-dropdown" id="quickAssignDropdown"></div>
                     </div>
                 </div>
                 <div class="lt-modal-footer">
@@ -1170,7 +1169,9 @@ function quickAssign(ticketId) {
                         label: u.display_name || u.username
                     }))
                 ];
-                lt.combobox.init(input, items, {
+                lt.typeahead.init(input, items, {
+                    minChars: 1,
+                    maxResults: 8,
                     onSelect: function(item) { _quickAssignUserId = item.value || null; }
                 });
             }