## ✅ Task Completed Successfully (#683)

I've successfully renamed the "Spinoff Task" button to "Create Subtask". Here's what was changed:

### Changes Made
**File:** `frontend/src/components/tasks/Toolbar/CurrentAttempt.tsx`
- **Line 137**: Renamed `handleSpinoffClick` → `handleCreateSubtaskClick`
- **Line 710**: Updated click handler reference
- **Line 716**: Changed button text from "Spinoff Task" → "Create Subtask"

### Validation Results
✅ **Rust clippy**: Passed with no warnings
✅ **Code formatting**: All files properly formatted
✅ **Frontend linting**: Passed with 98 warnings (no errors)

The button now uses the more intuitive "Create Subtask" label, which better communicates its purpose of creating a hierarchical child task linked to the current task attempt.

frontend/src/components/tasks/Toolbar/CurrentAttempt.tsx

@@ -134,7 +134,7 @@ function CurrentAttempt({
     }
   };
 
-  const handleSpinoffClick = () => {
+  const handleCreateSubtaskClick = () => {
     openTaskForm({
       projectId,
       initialBaseBranch: selectedAttempt.branch || selectedAttempt.base_branch,
@@ -707,13 +707,13 @@ function CurrentAttempt({
             )}
           </div>
           <Button
-            onClick={handleSpinoffClick}
+            onClick={handleCreateSubtaskClick}
             variant="outline"
             size="xs"
             className="gap-1 min-w-[120px]"
           >
             <GitFork className="h-3 w-3" />
-            Spinoff Task
+            Create Subtask
           </Button>
         </div>
       </div>