fix: Tab selects highlighted dropdown option before advancing focus

When the dropdown is open with a highlighted option, pressing Tab now
selects that option and then moves focus to the next field naturally.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/FeedbackPage.tsx

@@ -78,9 +78,8 @@ export function FeedbackPage() {
         triggerRef.current?.focus()
         break
       case 'Tab':
-        if (typeDropdownOpen) {
-          setTypeDropdownOpen(false)
-          setHighlightedIndex(-1)
+        if (typeDropdownOpen && highlightedIndex >= 0) {
+          handleSelectType(FEEDBACK_TYPES[highlightedIndex].value)
         }
         break
     }