implement vue-color in Apostrophe

[stuartromanek]

Summary

• Removes the vue-color dependency
• Implements vue-color component directly in Apostrophe
• Swap tinycolor2 for @ctrl/tinycolor and update usage accordingly

Note: This is a straight port. No API surfaces changed or additional features implemented.

✅ UI Tests passed here https://github.com/apostrophecms/testbed/actions/runs/11784024947

Related PRs
https://github.com/apostrophecms/testbed/pull/309

What are the specific steps to test this change?

1. npm run dev
2. Check a schema color field
3. Check the rich text color tool

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

If adding a new feature without an already open issue, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[boutell]

Since we're copying in a bunch of code here, we need to add a section to our LICENSE.md. After the existing material:

"Portions derived from vue-color require the following statement:"

And then the contents of the license file from vue-color, which is also MIT license (so fully compatible).

[stuartromanek]

@boutell [Like this]? (6b2c03a) No additional formatting?

[boutell]

Great