[Job States] Implement Job States

[KCui0327]

📖 Description
Define and implement the lifecycle states for jobs.

✅ Objectives

• Supported states:
  • Scheduled / Waiting (not yet taken by worker)
  • In Progress (worker has taken)
  • Success (job completed successfully, results available)
  • Error (job failed due to worker error)
  • Failure (worker terminated, must be rescheduled)
• Represent states as enum/constants in codebase

🎯 Acceptance Criteria

• All states are defined and implemented
• Jobs can only be in one state at a time
• State can be queried programmatically

[blobcode]

@redpinecube what's the status on this?

[redpinecube]

should be done by sunday