fix: 应用启动即绑定用户数据库（修复刷新/登录后数据库未就绪的白屏）

intern-log/src/db/auth.ts

@@ -67,8 +67,13 @@ export function clearCloudCreds(): void {
   localStorage.removeItem(CREDS_KEY)
 }
 
+let openedFor: string | null = null
+
 export function openUserDatabase(userId: string): void {
+  if (openedFor === userId && db) return
+  if (db) unbindDatabase()
   bindDatabase(new WorklogDB(LEGACY_DB_NAME + '_' + userId))
+  openedFor = userId
 }
 
 export async function createUser(username: string, password: string, migrateLegacy: boolean): Promise<Session> {
@@ -110,6 +115,7 @@ export async function login(username: string, password: string): Promise<Session
 export async function logoutUser(): Promise<void> {
   lockVault()
   unbindDatabase()
+  openedFor = null
   clearSession()
   clearCloudCreds()
 }
@@ -132,6 +138,7 @@ export async function deleteCurrentUser(): Promise<void> {
   if (!s) throw new Error('未登录')
   lockVault()
   unbindDatabase()
+  openedFor = null
   await Dexie.delete(LEGACY_DB_NAME + '_' + s.userId)
   await registry.user.delete(s.userId)
   clearSession()