feat: #3632634 Support optional taxonomy term colors from Color Field

Allows a Color Field attached to taxonomy terms to supply display colors, with translated values, optional opacity, field access checks, and cache metadata. Empty or inaccessible values fall back to the display defaults; Color Field remains optional.

Issue: #3632634

Dependencies

• #3632633: Make term counts configurable in every display and retire the duplicate count-list display

This source branch includes prerequisite commits. Keep this request in draft until those changes merge; then rebase onto 1.0.x and verify that only this issue’s change remains before marking it ready. The focused issue commit is e6c456377a98f7cd124667e09bd77f85d9492d0b.

Validation

2 functional tests passed with 47 assertions. Drupal/DrupalPractice coding standards and whitespace checks passed.

The integrated feature set also passed 13 functional tests with 292 assertions, plus browser checks for contextual-menu styling, theme link colors, and the Drupal-blue SVG fallback.