V9.0.0 beta.1

[silviuaavram]

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

Netlify deploy preview

https://deploy-preview-48178--material-ui.netlify.app/

Bundle size report

Bundle	Parsed size	Gzip size
@mui/material	0B(0.00%)	0B(0.00%)
@mui/lab	0B(0.00%)	0B(0.00%)
@mui/system	0B(0.00%)	0B(0.00%)
@mui/utils	0B(0.00%)	0B(0.00%)

Details of bundle changes

Generated by 🚫 dangerJS against 671e1c1

[Copilot]

Pull request overview

Prepares the repository for the v9.0.0-beta.1 release by bumping package versions and adding a new release entry to the root changelog.

Changes:

• Bump selected @mui/* package versions from 9.0.0-beta.0 to 9.0.0-beta.1.
• Bump @mui/internal-markdown from 3.0.5 to 3.0.6.
• Add 9.0.0-beta.1 release notes to CHANGELOG.md.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
packages/mui-utils/package.json	Version bump to 9.0.0-beta.1.
packages/mui-system/package.json	Version bump to 9.0.0-beta.1.
packages/mui-private-theming/package.json	Version bump to 9.0.0-beta.1.
packages/mui-material/package.json	Version bump to 9.0.0-beta.1.
packages/mui-material-pigment-css/package.json	Version bump to 9.0.0-beta.1.
packages/mui-lab/package.json	Version bump to 9.0.0-beta.1.
packages/mui-icons-material/package.json	Version bump to 9.0.0-beta.1.
packages/mui-docs/package.json	Version bump to 9.0.0-beta.1.
packages/mui-core-downloads-tracker/package.json	Version bump to 9.0.0-beta.1.
packages/markdown/package.json	Internal markdown package patch bump to 3.0.6.
package.json	Monorepo version bump to 9.0.0-beta.1.
CHANGELOG.md	Add release notes for 9.0.0-beta.1.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The monorepo root version is bumped to 9.0.0-beta.1, but several workspace packages still declare 9.0.0-beta.0 (e.g. @mui/codemod, @mui/types, @mui/styled-engine, @mui/material-nextjs, @mui/stylis-plugin-rtl). This version skew is likely to break publishing/consumption expectations for a coordinated v9 beta release. Either bump the remaining @mui/* package versions to 9.0.0-beta.1 as part of this release, or keep the root version at beta.0 and scope this PR to only the packages that are actually being released.

Suggested change

	"version": "9.0.0-beta.1",
	"version": "9.0.0-beta.0",