Canvas Entities 1.0.0-alpha1

First release. Bridges Drupal Canvas Content Templates to paragraph and
taxonomy_term entities: visually design a paragraph type or taxonomy
vocabulary in the Canvas editor and have it render automatically wherever
that entity appears.

Renamed from Canvas Paragraphs to reflect taxonomy_term support alongside
paragraphs. Also adds GitLab CI (lint + tests) and Kernel test coverage.

Experimental: lifecycle tracks Canvas's own roadmap
(drupal.org/project/canvas/issues/3498525), and the API may still change.