Migrate NFU subtype to tags, remove from UI

**Jira Ticket**: ALCS-2135

**Description**: As ALC staff, I want NFU subtypes to be tags so I can add more than one and they are front and centre instead of buried on the App Prep or Decision pages.

*Acceptance Criteria*
* Migrate proposal component and decision component NFU subtypes into tags
** dont add a tag if its already on the file
** *as per the attached file*
* Remove NFU type and subtype from the App Prep page
* Remove NFU type and subtype from the NFU Decision Component
* DO NOT REMOVE FIELDS FROM DATABASE
* Directors want to limit this to files submitted to the ALC after ... 2019 (when the legislation changed to break soil and fill and NARU out of NFU)

**Last Updated**: 2025-03-03 16:59

Start by tracing the proposal component, decision component, App Prep page, and NFU Decision Component mentioned in the issue, along with the existing tag handling. Before coding, clarify the missing 2019 cutoff details and the referenced attached file. Done means NFU subtypes are represented as non-duplicated tags for the intended files, the NFU fields are removed from both UI locations, and the database fields remain.

Written by the indexing model from the issue text.