Initialize Canvas Override module

Problem/Motivation

#3567225: Allow per-node override of Content Template via checkbox in node selector
#3520487: Refuse editing an individual node's component tree (and bring back after 1.0 once exposed slots are allowed)

Proposed resolution

Canvas Override lets site builders enable per-node Canvas layout editing on the full content view mode for selected content types — similar to Layout Builder overrides.

Nodes without a per-node layout fall back to the shared ContentTemplate default.

Features

• Opt-in per content type via the content type form.
• Auto-provisions a field_canvas_layout field and configures view displays.
• Adds a Canvas tab on nodes for editors.
• Reset route to revert a node back to the content type default layout.
• Works with config import and Drupal recipes.

Using the following patch for the Drupal Canvas module on
#3567225: Allow per-node override of Content Template via checkbox in node selector

      "drupal/canvas": {
        "feat: #3567225 Allow per-node override of Content Template via checkbox in node selector":
        "https://raw.githubusercontent.com/vardot/varbase-patches/refs/heads/patches/canvas--2026-04-21--3567225--mr-948.patch"
      }

Remaining tasks

• ✅ File an issue
• ✅ Addition/Change/Update/Fix
• ✅ Testing to ensure no regression
• ✅ Automated unit testing coverage
• ✅ Automated functional testing coverage
• ➖ UX/UI designer responsibilities
• ✅ Readability
• ✅ Accessibility
• ✅ Performance
• ✅ Security
• ✅ Documentation
• ✅ Code review by maintainers
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Release notes snippet
• ✅ Release canvas_override-1.0.0-alpha1

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• feat: #3582111 Initialize Canvas Override module