fix: remove stale persistLastVault and unused imports after rebase

.claude-pid

@@ -1 +1 @@
-3852
+

src/hooks/useVaultSwitcher.ts

@@ -1,6 +1,4 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import { invoke } from '@tauri-apps/api/core'
-import { isTauri, mockInvoke } from '../mock-tauri'
 import { pickFolder } from '../utils/vault-dialog'
 import { loadVaultList, saveVaultList } from '../utils/vaultListStore'
 import type { VaultOption } from '../components/StatusBar'
@@ -69,7 +67,6 @@ export function useVaultSwitcher({ onSwitch, onToast }: UseVaultSwitcherOptions)
 
   const switchVault = useCallback((path: string) => {
     setVaultPath(path)
-    persistLastVault(path)
     onSwitchRef.current()
   }, [])