Extend license/attribution field to support AI-generated and AI-assisted assets

Problem/Motivation

The current license/attribution field (license select + author/author_url + source/source_url) assumes a human creator and a licensable work. AI-generated assets break both assumptions:

• There is no clear "author" in the copyright sense for purely AI-generated output.
• The license select forces editors to assert a CC (or similar) rights claim that may not legally apply to AI-generated content.
• EU AI Act Art. 50 disclosure obligations apply from 2 August 2026 and require sites to label AI-generated/-manipulated content. This is not a nice-to-have, it is an approaching compliance requirement for deployers.

Key constraint: we cannot assume existing assets are human-created just because the field predates this feature. Any migration or default must treat existing creation types as unknown.

Proposed resolution

• Add a creation_type sub-field (human_created | ai_generated | ai_assisted) governing conditional sub-fields (ai_tool, ai_prompt, human_editor) via #states.
• Add a distinct license option for content with no asserted/no known copyright, rather than reusing existing e.g. CC entries for this case.
• Default new entries going forward as needed - leave unset/unknown as its own state.

Data migration / existing content

• New column(s) require a migration path (update hook) that sets creation_type to a neutral "unknown/unspecified" default
• Bulk-edit tooling: a View (or VBO-style bulk operation) listing assets by current attribution state, letting editors triage and bulk-assign creation_type where known, rather than requiring per-asset manual edits.
• This should be flagged as review work for site owners post-update (changelog/release note), since it affects legal disclosure obligations and not just display.

Display/rendering considerations

• Rendering of the attribution field is themeable/overridable per site and varies across sites using this module. For example, the OpenCulturas distribution ships a template override that renders attribution as a popover trigger styled as a © symbol - but that icon choice does not generalize to AI-generated content, since there is no copyright claim being made and reusing a © glyph could be misleading.
• The label "Attribution" remains valid and appropriate across all creation types and should stay the constant, translatable string. Only icons/visual triggers and the populated sub-fields should vary by creation_type.
• Provide sensible css classes. Any default icon/label for AI-disclosure should live in the template/formatter layer, not be baked into the field logic itself (let's not assume that/how any given site renders a trigger).

Remaining tasks / open questions

• Icon/visual convention for AI-generated vs. AI-assisted vs. human-created (needs design input; the EU Commission's proposed "AI"/"KI" visual label is a reference point, not necessarily one to copy verbatim).
• Confirm schema change strategy: new columns on existing field storage vs. a new field.
• Decide default license option label/machine name for the "no known copyright" case.
• Confirm whether human_editor is a separate role from the existing "author" field, or replaces it conditionally when creation_type is not human_created.

API/data model changes

• New field storage columns: creation_type, ai_tool, ai_prompt, human_editor.
• Widget: conditional visibility logic keyed on creation_type.
• Formatter: template changes to render the disclosure label independent of icon choice.

Issue text created with the assistance of Claude, based on human concept ;-)