fix(tasks): refine mobile board gestures

frontend/src/app/globals.css

@@ -1174,6 +1174,20 @@ html[data-bs-theme="dark"] .tasks-board-group-header-sticky {
    собственную область прокрутки. contain не передаёт скролл всей странице,
    когда пользователь дошёл до начала или конца конкретной ленты. */
 @media (max-width: 79.999rem) {
+  .tasks-task-card,
+  .tasks-board-column-header,
+  .tasks-board-subcolumn-header {
+    -webkit-touch-callout: none;
+    -webkit-user-select: none;
+    user-select: none;
+  }
+
+  .tasks-task-card img,
+  .tasks-board-column-header img,
+  .tasks-board-subcolumn-header img {
+    -webkit-user-drag: none;
+  }
+
   .tasks-board-column-header,
   .tasks-board-subcolumn-header {
     box-shadow: none !important;

frontend/src/app/tasks/page.tsx

@@ -2128,10 +2128,10 @@ function AddColumnCard({
     <button
       type="button"
       onClick={onClick}
-      style={{ height: cardHeight }}
-      className="group flex min-w-[18rem] self-start flex-col items-center justify-center rounded-xl border border-dashed border-[var(--border-subtle)] bg-[var(--surface-muted)] p-4 text-center transition hover:border-[var(--accent-primary)] hover:bg-[var(--surface-elevated)] xl:sticky xl:top-0"
+      style={{ "--tasks-add-column-height": `${cardHeight}px` } as CSSProperties}
+      className="group flex h-16 min-h-16 min-w-[18rem] self-start items-center justify-center gap-2 rounded-xl border border-dashed border-[var(--border-subtle)] bg-[var(--surface-muted)] px-4 text-center transition hover:border-[var(--accent-primary)] hover:bg-[var(--surface-elevated)] xl:sticky xl:top-0 xl:h-[var(--tasks-add-column-height)] xl:flex-col xl:gap-0 xl:p-4"
     >
-      <span className="app-selected mb-3 flex h-10 w-10 items-center justify-center rounded-xl transition group-hover:scale-105">
+      <span className="app-selected flex h-9 w-9 items-center justify-center rounded-xl transition group-hover:scale-105 xl:mb-3 xl:h-10 xl:w-10">
         <Plus size={18} />
       </span>
       <span className="text-sm font-semibold text-[var(--foreground)]">