fix: separate subtask expand chevron from detail view icon (#63)

Split TaskItem into two independent states:
- `expanded` (chevron): toggles subtask visibility, only shown when
  subtasks exist
- `detailOpen` (search icon + title click): opens detail panel with
  notes, priority, edit/delete actions

The two actions are fully independent — expanding subtasks does not
open the detail view and vice versa.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/src/components/TaskItem.tsx

@@ -9,6 +9,7 @@ import {
   Calendar,
   Repeat,
   Check,
+  Search,
 } from "lucide-react";
 import { useTranslation } from "react-i18next";
 import type { Task } from "@/lib/types";
@@ -40,6 +41,7 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
   const { t } = useTranslation();
   const router = useRouter();
   const [expanded, setExpanded] = useState(false);
+  const [detailOpen, setDetailOpen] = useState(false);
   const [editing, setEditing] = useState(false);
   const [title, setTitle] = useState(task.title);
   const [notes, setNotes] = useState(task.notes || "");
@@ -123,17 +125,21 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
       >
         {/* Main row */}
         <div className="flex items-center gap-2 px-3 py-2">
-          {/* Expand toggle */}
-          <button
-            onClick={() => setExpanded(!expanded)}
-            className="p-0.5 text-foreground/40 hover:text-foreground shrink-0"
-          >
-            {expanded ? (
-              <ChevronDown size={14} />
-            ) : (
-              <ChevronRight size={14} />
-            )}
-          </button>
+          {/* Expand subtasks toggle — only shown when subtasks exist */}
+          {subtasks.length > 0 ? (
+            <button
+              onClick={() => setExpanded(!expanded)}
+              className="p-0.5 text-foreground/40 hover:text-foreground shrink-0"
+            >
+              {expanded ? (
+                <ChevronDown size={14} />
+              ) : (
+                <ChevronRight size={14} />
+              )}
+            </button>
+          ) : (
+            <span className="w-[18px] shrink-0" />
+          )}
 
           {/* Checkbox */}
           <button
@@ -147,12 +153,12 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
             {task.completed && <Check size={12} />}
           </button>
 
-          {/* Title */}
+          {/* Title — click opens detail */}
           <span
             className={`flex-1 text-sm cursor-pointer ${
               task.completed ? "line-through text-foreground/50" : ""
             }`}
-            onClick={() => setExpanded(!expanded)}
+            onClick={() => setDetailOpen(!detailOpen)}
           >
             {task.title}
           </span>
@@ -174,10 +180,20 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
               {subtasks.filter((s) => s.completed).length}/{subtasks.length}
             </span>
           )}
+
+          {/* Detail view toggle */}
+          <button
+            onClick={() => setDetailOpen(!detailOpen)}
+            className={`p-0.5 shrink-0 transition-colors ${
+              detailOpen ? "text-bleu" : "text-foreground/30 hover:text-foreground/60"
+            }`}
+          >
+            <Search size={14} />
+          </button>
         </div>
 
-        {/* Expanded view */}
-        {expanded && (
+        {/* Detail view */}
+        {detailOpen && (
           <div className="px-3 pb-3 pt-1 border-t border-border-light dark:border-border-dark">
             {editing ? (
               <div className="space-y-2">
@@ -284,7 +300,7 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
       </div>
 
       {/* Subtask form */}
-      {showSubtaskForm && expanded && (
+      {showSubtaskForm && detailOpen && (
         <div style={{ marginLeft: 24 }} className="mb-1.5">
           <TaskForm
             listId={task.listId}
@@ -294,8 +310,8 @@ export function TaskItem({ task, subtasks = [], depth = 0 }: TaskItemProps) {
         </div>
       )}
 
-      {/* Subtasks */}
-      {subtasks.map((sub) => (
+      {/* Subtasks — toggled by chevron */}
+      {expanded && subtasks.map((sub) => (
         <TaskItem key={sub.id} task={sub} depth={depth + 1} />
       ))}
     </div>