feat: add @cds/core shim

This commit copies the shim from `@cds/core@6.2.5` to `@clr/ui`.

We are moving the shim to the `@clr/ui` package to allow both to be
evolved together. Otherwise, changes to the custom property API exposed
by `@clr/ui` will require changes in a separate package (and separate repo).
This would cause version synchronization difficulties.

How to update:

The file path in applications should be updated as follows:
'@cds/core/styles/shim.clr-ui.min.css' -> '@clr/ui/shim.cds-core.min.css'

That's it, just a simple find and replace.

.prettierrc.js

@@ -13,4 +13,12 @@ module.exports = {
   trailingComma: 'es5',
   bracketSpacing: true,
   arrowParens: 'avoid',
+  overrides: [
+    {
+      files: 'projects/ui/src/shim.cds-core.scss',
+      options: {
+        printWidth: 200,
+      },
+    },
+  ],
 };

.storybook/main.js

@@ -7,7 +7,7 @@
 const TsconfigPathsPlugin = require('tsconfig-paths-webpack-plugin');
 
 module.exports = {
-  stories: ['./stories/**/*.stories.{ts,mdx}'],
+  stories: ['./**/*.stories.{ts,mdx}'],
   addons: ['@storybook/addon-essentials', '@storybook/addon-a11y'],
   framework: '@storybook/angular',
   core: {

.storybook/pages/cds-core-shim.stories.mdx

@@ -0,0 +1,42 @@
+import { Meta } from '@storybook/addon-docs';
+
+<Meta title="cds-core shim" />
+
+# @cds/core shim
+
+Clarity provides a theme the enables `@clr/ui` applications to consume the Clarity Core design
+tokens and theme system. Once installed, `@clr/ui` applications will be able to use all Clarity Core
+color themes available today, in particular the color contrast adjustments in the light and dark
+themes. The shim maps colors to the `@cds/core` design token system. Typography and spacing are
+not affected. If your application does not use `@clr/ui`, this shim is not needed.
+
+Follow the [Getting Started](https://storybook.core.clarity.design/?path=/story/documentation-getting-started--page)
+directions for Clarity Core, including loading the relevant CSS files and setting the `cds-theme`
+attribute on the body tag. The shim will not be applied to `@clr/ui` or `@clr/angular` components
+without this attribute.
+
+Import and load the CSS shim file last after `@clr/ui` global CSS. This will ensure that the shim can
+override the `@clr/ui` values appropriately.
+
+```css
+@import 'modern-normalize/modern-normalize.css';
+@import '@cds/core/global.min.css'; // provides the Clarity Core design tokens
+@import '@cds/core/styles/theme.dark.min.css'; // to allow dark mode with cds-theme="dark"
+@import '@clr/ui/clr-ui.min.css'; // @clr/ui CSS (this should already be imported by your application)
+@import '@cds/ui/shim.cds-core.min.css'; // the shim file
+```
+
+## Dark Mode
+
+Clarity Core's dark mode should replace the `@clr/ui` dark mode. Remove any reference to the `@clr/ui`
+dark mode file from the source code and toggle dark mode by changing the `cds-theme` attribute to "dark."
+
+## Adoption
+
+We fully support the `@cds/core` shim as the path forward for ng-clarity. But we need your help. The
+shim is currently optional, but the only way to improve the Shim is to get feedback from teams as
+they adopt it in their projects/products. We recomend new projects to use the shim from the start.
+For existing projects, we ask teams to start adopting it to help us test it and provide feedback.
+
+Our goal is mature the shim to a point where it can be the default (and later the only) option for
+theming Clarity.

.storybook/public/preview.css

@@ -11,4 +11,4 @@
 @import '@cds/core/styles/module.typography.min.css';
 @import '@cds/core/styles/theme.dark.min.css';
 @import '@cds/core/styles/theme.high-contrast.min.css';
-@import '@cds/core/styles/shim.clr-ui.min.css';
+@import '../../dist/clr-ui/shim.cds-core.css';

projects/demo/src/styles.scss

@@ -10,7 +10,7 @@
 @import '@cds/core/styles/module.typography.min.css';
 @import '@cds/core/styles/theme.dark.min.css';
 @import '@cds/core/styles/theme.high-contrast.min.css';
-@import '@cds/core/styles/shim.clr-ui.min.css';
+@import './../../ui/src/shim.cds-core';
 @import './app/_utils/clarity-variables';
 @import '../../angular/src/utils/variables/variables';