feat: Enhance sample pack retrieval with project filtering and update AI service methods

Commit notes

- Updated the sample pack retrieval endpoint to support optional project filtering based on user input. - Refactored AI service methods to utilize the new `generateText` function, improving output handling for copy suggestions, tagging, and categorization. - Simplified the API calls in the frontend to accommodate the new project filtering logic, ensuring a more tailored user experience. - Added state management for project selection in the workspace store to enhance project visibility options.