feat: add AI Studio controller/routes gated by per-artist enable flag

[Mainnet-ops]

Description

Please include a summary of the change and which issue is fixed.

Fixes # (issue)

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation update

Closes #276
Closes #278
Closes #279
Closes #280

Checklist:

• My code follows the coding conventions
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[drips-wave]

@Mainnet-ops Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

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