Allow adding multiple folders to a worker

[benjaminshafii]

Problem\nUsers can only attach a single folder to a worker, which is limiting for real projects.\n\n## Expected behavior\nUsers should be able to add and manage multiple folders per worker.\n\n## Why this matters\nMany workflows span several directories (app, shared libs, config repos, docs). Forcing one folder creates friction and workarounds.\n\n## Suggested direction\n- Support multiple folder entries in worker configuration\n- Let users add/remove/reorder folders\n- Preserve this list across sessions