refactor: enhance code comments for clarity and maintainability across multiple files

frontend/src/components/organisms/TaskBoard.tsx

@@ -155,6 +155,7 @@ export const TaskBoard = memo(function TaskBoard({
     return positions;
   }, []);
 
+  // Animate card reordering smoothly by applying FLIP whenever layout positions change.
   useLayoutEffect(() => {
     const cardRefsSnapshot = cardRefs.current;
     if (animationRafRef.current !== null) {
@@ -275,6 +276,7 @@ export const TaskBoard = memo(function TaskBoard({
     return buckets;
   }, [tasks]);
 
+  // Keep drag/drop state and payload handling centralized for column move interactions.
   const handleDragStart =
     (task: Task) => (event: React.DragEvent<HTMLDivElement>) => {
       if (readOnly) {
@@ -344,6 +346,7 @@ export const TaskBoard = memo(function TaskBoard({
     >
       {columns.map((column) => {
         const columnTasks = grouped[column.status] ?? [];
+        // Derive review tab counts and the active subset from one canonical task list.
         const reviewCounts =
           column.status === "review"
             ? columnTasks.reduce(

frontend/src/components/ui/dropdown-select.tsx

@@ -40,6 +40,7 @@ type DropdownSelectProps = {
   emptyMessage?: string;
 };
 
+// Resolve trigger placeholder text with explicit prop override first, then accessible fallback.
 const resolvePlaceholder = (ariaLabel: string, placeholder?: string) => {
   if (placeholder) {
     return placeholder;
@@ -51,6 +52,7 @@ const resolvePlaceholder = (ariaLabel: string, placeholder?: string) => {
   return trimmed.endsWith("...") ? trimmed : `${trimmed}...`;
 };
 
+// Resolve search input placeholder from explicit override or a normalized aria label.
 const resolveSearchPlaceholder = (
   ariaLabel: string,
   searchPlaceholder?: string,
@@ -107,6 +109,7 @@ export default function DropdownSelect({
     handleOpenChange(false);
   };
 
+  // Reset list scroll when opening or refining search so results start at the top.
   React.useEffect(() => {
     if (!open) {
       return;