feat: enhance mobile vault filter UI and improve styling for better usability

webapp/src/lib/i18n/locales/en.ts

@@ -758,6 +758,7 @@ const en: Record<string, string> = {
   "txt_search_sends": "Search sends...",
   "txt_session_refresh_failed": "Session refresh failed. Please sign in again.",
   "txt_search_your_secure_vault": "Search your secure vault...",
+  "txt_search_items_count": "Search within {count} items...",
   "txt_clear_search": "Clear search",
   "txt_clear_search_esc": "Clear search (Esc)",
   "txt_sort": "Sort",

webapp/src/lib/i18n/locales/es.ts

@@ -758,6 +758,7 @@ const es: Record<string, string> = {
   "txt_search_sends": "Buscar envíos...",
   "txt_session_refresh_failed": "Error al actualizar la sesión. Inicia sesión de nuevo.",
   "txt_search_your_secure_vault": "Buscar en su bóveda segura...",
+  "txt_search_items_count": "Buscar entre {count} elementos...",
   "txt_clear_search": "Limpiar búsqueda",
   "txt_clear_search_esc": "Limpiar búsqueda (Esc)",
   "txt_sort": "Ordenar",

webapp/src/lib/i18n/locales/ru.ts

@@ -758,6 +758,7 @@ const ru: Record<string, string> = {
   "txt_search_sends": "Поиск отправляет...",
   "txt_session_refresh_failed": "Не удалось обновить сеанс. Войдите снова.",
   "txt_search_your_secure_vault": "Найдите свое безопасное хранилище...",
+  "txt_search_items_count": "Поиск по {count} элементам...",
   "txt_clear_search": "Очистить поиск",
   "txt_clear_search_esc": "Очистить поиск (Esc)",
   "txt_sort": "Сортировать",

webapp/src/lib/i18n/locales/zh-CN.ts

@@ -758,6 +758,7 @@ const zhCN: Record<string, string> = {
   "txt_search_sends": "搜索 Send...",
   "txt_session_refresh_failed": "会话刷新失败，请重新登录",
   "txt_search_your_secure_vault": "搜索你的密码库...",
+  "txt_search_items_count": "共 {count} 项中搜索...",
   "txt_clear_search": "清空搜索",
   "txt_clear_search_esc": "清空搜索（Esc）",
   "txt_sort": "排序",

webapp/src/lib/i18n/locales/zh-TW.ts

@@ -758,6 +758,7 @@ const zhTW: Record<string, string> = {
   "txt_search_sends": "搜索 Send...",
   "txt_session_refresh_failed": "會話刷新失敗，請重新登入",
   "txt_search_your_secure_vault": "搜索你的密碼庫...",
+  "txt_search_items_count": "在共 {count} 項中搜索...",
   "txt_clear_search": "清空搜索",
   "txt_clear_search_esc": "清空搜索（Esc）",
   "txt_sort": "排序",