Prepare NXCTF pre-release event

[ariafatah0711]

Goal

Prepare the initial pre-release NXCTF event before the public platform launch.

Focus:

• limited challenge set
• active learning environment
• public testing and feedback
• beginner-friendly participation
• reward-based challenges
• infrastructure validation
• platform readiness

The event should help validate:

• challenge workflows
• platform stability
• scoring systems
• event operations
• participant experience