[M2] Set Ghost Market app as main scene

[BotTony329]

Task

• Task ID:
• Task name:
• Owner: Claude / Codex
• Objective:
• Scope:

Implementation

• Changes:
• Files changed:
• Interfaces used:
• Core files modified: None / list and justify
• Architecture implications:

Validation

• Tests added or updated:
• Commands run:
• Manual validation:
• Screenshots or recordings:
• Known issues:
• Handoff notes:

Checklist

• Read AGENTS.md
• Read AI_HANDOFF.md
• No direct push to main or develop
• No unrelated refactoring
• No balance values scattered as magic numbers
• Tests added or updated
• Existing tests pass
• Documentation updated
• Frozen interface changes are explicitly documented