Support optional taxonomy term colors from Color Field

Problem/Motivation

Terms may already have an editorially assigned color. Wordcloud should be able to use it without requiring Color Field on every installation.

Proposed resolution

• Add an optional Term color field selector listing Color Fields attached to taxonomy terms.
• Use the first visible color value from the translated term, including field opacity when enabled.
• Apply the color to SVG words and HTML term text, with tinted Pill and Badge backgrounds and borders.
• Validate literal colors before exposing CSS, respect field access, and propagate field and term cache metadata.
• Fall back to the selected palette or display defaults for empty, missing, invalid, or inaccessible values. Keep Color Field optional.

Remaining tasks

Split the local implementation into a focused patch or merge request, attach it here, review, and merge.

Validation

Verify all displays with drupal/color_field installed, opacity and storage formats, denied fields, missing or empty values, and cache invalidation after term color changes. Run base display tests without Color Field enabled.