Add authentication layer for debug endpoints

[AndPuQing]

Problem

The debug endpoints are currently exposed without authentication, which poses a security risk as they expose full job details and internal state.

Proposed Solution

Implement an authentication/authorization layer that:

• Requires authentication for debug endpoints
• Supports user-based access control
• Integrates with existing user context from job submissions
• Allows admin-level access for debug operations

Security Considerations

• Debug endpoints should only be accessible to authorized users
• Consider role-based access (admin vs regular users)
• Add audit logging for debug endpoint access

References

• Current warning in src/multicall/gflowd/server.rs:3-7