Bug / Improvement: Prevent Duplicate Dataset Names in OLIM

[isaquepim]

Context

Currently, it is possible to upload multiple datasets with the same name into OLIM.

This creates ambiguity, since it becomes unclear:

• Which dataset OLIM will use internally
• How the system resolves name conflicts
• Whether one dataset overrides the other silently

Proposed Solution

Enforce unique dataset names at the database level.

• Add a UNIQUE constraint on the dataset name field
• Validate name uniqueness before upload-
• Return a clear error message if a duplicate name is detected