Implement backend support for tag colors

[gustavosbarreto]

This feature will enable storing and retrieving color information associated with tags. Although there is no UI implementation required at this stage, the backend should be ready to handle color attributes for tags.

Database Changes

• Add a new field (e.g., color) to the tags schema in the database to store color information.
• Ensure the field supports common color formats (e.g., HEX).

API Changes

• Update the API endpoints for creating and editing tags to accept a color attribute.
• Update the API endpoints for retrieving tags to include the color attribute in the response.

Validation

Validate the color field to ensure it adheres to a valid format (e.g., HEX codes like #FFFFFF).

Backward Compatibility

Ensure existing tags without color information remain functional and default to empty (null value).

Testing

Add unit and integration tests to verify the proper handling of the color attribute in all relevant operations.

[haller33]

Since peers review, there is new directions for the solution required.:

feat: tags collection redesign

• Add primary key to tags to include tenantID/namespace
• Make tenant the primary granularity level for the tags collection (has previously are)
• Implement cascading operations (rename, delete) across all references including the new tags collection
• Update the reference of the use of tags to use new tags collection as main source
• Return array of objects instead of previous array of strings on tags default route