perf: preload and cache countdowns

frontend/src/style.test.ts

@@ -156,6 +156,13 @@ describe('mobile touch targets', () => {
 })
 
 describe('unified floating add interaction', () => {
+  it('preloads countdowns after authentication', () => {
+    expect(app).toContain('void preloadCountdowns()')
+    expect(app).toContain("const active = await api('/countdowns')")
+    expect(app).toContain("const archived = await api('/countdowns?archived=true')")
+    expect(app).toContain('writeCountdownCache(active ?? [], archived ?? [])')
+  })
+
   it('reuses one draggable FAB component for task, habit, and countdown views', () => {
     expect(app).toContain("import FloatingAddButton from './components/FloatingAddButton.vue'")
     expect(app).toContain('<FloatingAddButton')
@@ -254,7 +261,7 @@ describe('sidebar layout', () => {
   })
 
   it('loads archived lists during bootstrap so archived rows are visible after refresh', () => {
-    expect(app).toContain('expandedFolders.value = new Set(folders.value.map((folder) => folder.id))\n      await loadArchivedLists()\n      await loadAll()')
+    expect(app).toContain('expandedFolders.value = new Set(folders.value.map((folder) => folder.id))\n      await loadArchivedLists()\n      void preloadCountdowns()\n      await loadAll()')
   })
 
   it('styles archived rows through the new list-row-main structure', () => {