Refactor market routes and enhance sample pack retrieval logic

Commit notes

- Updated the GetPublicPack handler to accept both slug and ID for retrieving sample packs, improving flexibility in accessing packs. - Removed deprecated routes for market packs and updated frontend routing to reflect the new structure, enhancing navigation. - Introduced a new studio route for creators, replacing the previous creator route, to streamline user experience. - Updated header and various components to link to the new studio route, ensuring consistency across the application. - Cleaned up unused route types and files, improving code maintainability and clarity.