fix(KB-259): update subtask button tooltip for live feature

- Update subtask button tooltip from "coming soon" to "Break down into AI-generated subtasks"

- Apply tooltip fix to both QuickEntryBox and InlineCreateCard components

- Add changeset for patch release

.changeset/fix-subtask-button-tooltip.md

@@ -0,0 +1,7 @@
+---
+"@dustinbyrne/kb": patch
+---
+
+Update subtask button tooltip to reflect feature availability
+
+The Subtask button tooltip now correctly indicates "Break down into AI-generated subtasks" instead of "coming soon". The subtask breakdown feature with AI-generated subtasks, manual editing, and batch creation has been available and fully functional.

packages/dashboard/app/components/InlineCreateCard.tsx

@@ -666,7 +666,7 @@ export function InlineCreateCard({
                 onClick={handleSubtaskClick}
                 disabled={!description.trim()}
                 data-testid="subtask-button"
-                title="Break down into subtasks (coming soon)"
+                title="Break down into AI-generated subtasks"
               >
                 <ListTree size={12} style={{ verticalAlign: "middle" }} />
                 Subtask

packages/dashboard/app/components/QuickEntryBox.tsx

@@ -614,7 +614,7 @@ export function QuickEntryBox({ onCreate, addToast, tasks = [], availableModels,
                   onClick={handleSubtaskClick}
                   disabled={!description.trim()}
                   data-testid="subtask-button"
-                  title="Break down into subtasks (coming soon)"
+                  title="Break down into AI-generated subtasks"
                 >
                   <ListTree size={12} style={{ verticalAlign: "middle" }} />
                   Subtask