feat(cli): make --config a global option

[YuMo12268]

Summary

• Make --config a global CLI option shared by all runtime modes
• Allow --config to be specified at different subcommand levels
• Forward the global config path to client, coordinator, worker, agent, and manager-spawned workers
• Update manager process detection to recognize workers started with root-level --config
• Update client, coordinator, worker, and manager guides

[YuMo12268]

@un-lock-able Could you please review this PR? Thanks!