feat: add creator route constants and replace repeated route strings

[shogun444]

Closes #47

Summary

• Added creator route constants in src/constants/creator.constants.ts
• Replaced hardcoded /creators and / in creator routing with constants
• No behavior changes

Testing

• pnpm lint
• pnpm build
• pnpm exec prisma generate (not required)

Checklist

• Linked issue or backlog item (Add creator endpoint route constants #47)
• No secrets or live credentials added
• Docs updated if setup or env changed (not required)
• Change is scoped to one problem

[drips-wave]

@shogun444 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! 🚀

Learn more about application limits