feat: 登录即自动绑定云端并同步，免手动配置

intern-log/src/db/auth.ts

@@ -49,6 +49,24 @@ function clearSession(): void {
   localStorage.removeItem(SESSION_KEY)
 }
 
+// 云端凭据：与本地登录同账号同密码，用于登录后自动云同步（保存在本机浏览器）
+const CREDS_KEY = 'dsh_cloud_creds'
+export function setCloudCreds(username: string, password: string): void {
+  localStorage.setItem(CREDS_KEY, JSON.stringify({ username, password }))
+}
+export function getCloudCreds(): { username: string; password: string } | null {
+  try {
+    const raw = localStorage.getItem(CREDS_KEY)
+    if (!raw) return null
+    const c = JSON.parse(raw)
+    if (c && c.username && c.password) return c as { username: string; password: string }
+  } catch { /* 忽略损坏数据 */ }
+  return null
+}
+export function clearCloudCreds(): void {
+  localStorage.removeItem(CREDS_KEY)
+}
+
 export function openUserDatabase(userId: string): void {
   bindDatabase(new WorklogDB(LEGACY_DB_NAME + '_' + userId))
 }
@@ -71,6 +89,7 @@ export async function createUser(username: string, password: string, migrateLega
   }
   const session: Session = { userId: id, username: name }
   setSession(session)
+  setCloudCreds(session.username, password)
   if (copied) showToastCopied(copied)
   return session
 }
@@ -84,6 +103,7 @@ export async function login(username: string, password: string): Promise<Session
   openUserDatabase(rec.id)
   const session: Session = { userId: rec.id, username: rec.username }
   setSession(session)
+  setCloudCreds(session.username, password)
   return session
 }
 
@@ -91,6 +111,7 @@ export async function logoutUser(): Promise<void> {
   lockVault()
   unbindDatabase()
   clearSession()
+  clearCloudCreds()
 }
 
 export async function changeLoginPassword(oldPwd: string, newPwd: string): Promise<void> {
@@ -114,6 +135,7 @@ export async function deleteCurrentUser(): Promise<void> {
   await Dexie.delete(LEGACY_DB_NAME + '_' + s.userId)
   await registry.user.delete(s.userId)
   clearSession()
+  clearCloudCreds()
 }
 
 // 旧单机数据检测与迁移（迁移只复制，不删除原库，作为安全兜底）