Delete_dataset

[skull8888888]

[!IMPORTANT] Add DELETE method to route.ts for dataset deletion with user permission checks and error handling.

• Behavior:
  • Adds DELETE method to route.ts for deleting datasets by datasetIds.
  • Checks if the current user is a member of the project before proceeding.
  • Returns 403 if user is not a member, 400 if no datasetIds are provided, and 500 on deletion error.
• Database:
  • Uses db.delete with conditions on datasets.id and datasets.projectId to delete datasets.

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