support custom workspaces

[Shandelier]

Title: workspace from openclaw.json is ignored

Description:

The app does not respect the workspace folder defined in openclaw.json.

My config:

{
"agents": {
"defaults": {
"workspace": "~/.openclaw/workspace"
}
}
}

Expected behavior:
The application should use ~/.openclaw/workspace as the active workspace directory.

Actual behavior:
The configured workspace is ignored. As a result, I cannot see my prompt files or any of my tasks.