Fix inline code font size in headings

[rezrah]

Before	After

Before	After

[Copilot]

Pull Request Overview

This PR fixes the font size of inline code inside headings and adjusts spacing under React code blocks, along with updating an example and the changeset.

• Add CSS rule so inline <code> in headings inherits heading font size
• Define --spacing custom property for code blocks and update spacing in example
• Update example MDX and changelog entry

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
packages/theme/css/prose.module.css	New rule to make inline code in headings inherit font-size
packages/theme/components/layout/code-block/ReactCodeBlock.module.css	Added --spacing custom property for code block spacing
packages/site/content/content-example/kitchen-sink.mdx	Added demo heading with inline code
.changeset/khaki-mugs-cover.md	Updated changelog to reflect CSS and spacing fixes

Comments suppressed due to low confidence (1)

packages/theme/css/prose.module.css:215

• [nitpick] Consider adding a visual or snapshot test to verify that inline code within headings correctly inherits the heading font size across supported browsers.

.Prose :is(h1, h2, h3, h4, h5, h6):has(code) code:not(:global(.custom-component) code) {