fix(auth): 5 BUG 修复 — refresh token 持久化 + 密码验证 + 浏览器兼容

BUG-1 (P1): LoginPage 注册密码验证从 6 位改为 8 位，与后端一致
BUG-2 (P0): refresh token 持久化到 OS keyring + restoreSession 三级恢复
  (access token → refresh token → cookie auth) + saveSaaSSession 改为 await
BUG-3 (P0): Tauri 聊天路由降级问题，根因同 BUG-2（会话恢复失败）
BUG-4 (P1): App.tsx 跳过 Onboarding 改用 agentStore（兼容所有 client），
  Workspace.tsx Tauri invoke 改为动态 import 避免浏览器崩溃
BUG-5: tauri.conf.json createUpdaterArtifacts 改为 boolean true

desktop/src/components/LoginPage.tsx

@@ -170,8 +170,8 @@ export function LoginPage() {
       setLocalError('邮箱格式不正确');
       return;
     }
-    if (password.length < 6) {
-      setLocalError('密码长度至少 6 个字符');
+    if (password.length < 8) {
+      setLocalError('密码长度至少 8 个字符');
       return;
     }
     if (password !== confirmPassword) {
@@ -427,7 +427,7 @@ export function LoginPage() {
                       type={showPassword ? 'text' : 'password'}
                       value={password}
                       onChange={(e) => setPassword(e.target.value)}
-                      placeholder={isRegister ? '密码（至少 6 位）' : '密码'}
+                      placeholder={isRegister ? '密码（至少 8 位）' : '密码'}
                       autoComplete={isRegister ? 'new-password' : 'current-password'}
                       disabled={isLoading}
                       className={cn(inputClass, 'pr-10')}

desktop/src/components/Settings/Workspace.tsx

@@ -1,5 +1,4 @@
 import { useEffect, useState } from 'react';
-import { invoke } from '@tauri-apps/api/core';
 import { useConfigStore } from '../../store/configStore';
 import { silentErrorHandler } from '../../lib/error-utils';
 
@@ -11,13 +10,14 @@ export function Workspace() {
   const [projectDir, setProjectDir] = useState('~/.zclaw/zclaw-workspace');
   const [dirStats, setDirStats] = useState<{ fileCount: number; totalSize: number } | null>(null);
 
-  // Load real directory stats via Tauri command
+  // Load real directory stats via Tauri command (safe for browser mode)
   const loadDirStats = async (dir: string) => {
     try {
+      const { invoke } = await import('@tauri-apps/api/core');
       const stats = await invoke<{ file_count: number; total_size: number }>('workspace_dir_stats', { path: dir });
       setDirStats({ fileCount: stats.file_count, totalSize: stats.total_size });
     } catch {
-      // Command may not exist in all modes — fallback to workspaceInfo
+      // Not in Tauri environment or command unavailable — fallback to workspaceInfo
     }
   };