fix(desktop): collapse session task bar by default

Task card was expanded by default and overlapped the main chat area
whenever todos appeared. Start collapsed and reset expanded state on
clearTasks so new sessions also begin collapsed; users can click the
header to expand when needed.

desktop/src/stores/cliTaskStore.ts

@@ -36,7 +36,7 @@ type CLITaskStore = {
 export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
   sessionId: null,
   tasks: [],
-  expanded: true,
+  expanded: false,
   completedAndDismissed: false,
 
   fetchSessionTasks: async (sessionId) => {
@@ -89,7 +89,7 @@ export const useCLITaskStore = create<CLITaskStore>((set, get) => ({
   },
 
   clearTasks: () => {
-    set({ sessionId: null, tasks: [], completedAndDismissed: false })
+    set({ sessionId: null, tasks: [], completedAndDismissed: false, expanded: false })
   },
 
   toggleExpanded: () => {