[internal] Prepare libraries for first v9 alpha release

[silviuaavram]

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

[Copilot]

Pull request overview

This PR prepares MUI libraries for a v9 alpha release by updating documentation URLs, package versions, and adding migration documentation. However, there's a critical discrepancy: the PR title says "v7 alpha release" but all changes are for v9.

Changes:

• Updates all documentation URLs from https://mui.com to https://next.mui.com for the v9 alpha pre-release
• Changes package installation instructions from @latest to @next tags across all documentation
• Updates internal workspace dependencies from workspace:^ to workspace:* for packages releasing together in v9
• Adds v9 migration guide documentation and updates version selectors to include v7 as a previous version

Reviewed changes

Copilot reviewed 83 out of 84 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
packages/mui-system/src/createBreakpoints/createBreakpoints.d.ts	Updates API documentation URLs to next.mui.com domain
packages/mui-system/src/Grid/deleteLegacyGridProps.ts	Updates error message URL to next.mui.com
packages/mui-system/src/Grid/Grid.test.js	Updates test expectation to match error message URL change
packages/mui-system/package.json	Updates workspace dependencies to use * version for v9 release
packages/mui-system/README.md	Updates install command to use @next tag and documentation URL
packages/mui-styled-engine/README.md	Updates documentation URL to next.mui.com
packages/mui-styled-engine-sc/README.md	Updates documentation URL to next.mui.com
packages/mui-private-theming/package.json	Updates @mui/utils workspace dependency version
packages/mui-material/src/styles/createThemeNoVars.js	Updates error message documentation URL
packages/mui-material/package.json	Updates workspace dependencies for v9 release
packages/mui-material/README.md	Updates install command and documentation URL
packages/mui-lab/package.json	Updates workspace dependencies for v9 release
packages/mui-lab/README.md	Updates install commands and documentation URL
packages/mui-icons-material/package.json	Updates workspace dependency versions
packages/mui-icons-material/README.md	Updates install commands and documentation URLs
packages/mui-docs/README.md	Updates install commands to use @next tag
packages/mui-codemod/README.md	Updates all codemod command examples to use @next tag
packages/api-docs-builder-core/materialUi/projectSettings.ts	Updates base API URL to next.mui.com
examples/*/package.json (multiple)	Updates @mui packages to use "next" version in all examples
examples/*/README.md (multiple)	Updates documentation URLs to next.mui.com
docs/translations/translations.json	Adds v9 upgrade translations
docs/src/modules/sandbox/*.test.js	Updates test expectations for @next package versions
docs/src/modules/sandbox/Dependencies.ts	Changes default npm tag from "latest" to "next"
docs/src/modules/components/Head.tsx	Updates canonical URL host to next.mui.com
docs/pages/system/migration/upgrade-to-v9.js	Adds v9 migration page component
docs/pages/material-ui/migration/upgrade-to-v9.js	Adds v9 migration page component
docs/pages/_app.js	Adds v7 to version selectors for Material UI and System
docs/package.json	Updates deploy script to push to "next" branch; updates workspace dependencies
docs/data/system/pages.ts	Adds v9 upgrade page to System navigation
docs/data/system/migration/migration-to-v9/migration-to-v9.md	Creates System v9 migration guide
docs/data/system/getting-started/installation/installation.md	Updates install commands to use @next tag
docs/data/material/pages.ts	Adds v9 upgrade section to Material UI navigation
docs/data/material/migration/upgrade-to-v7/upgrade-to-v9/upgrade-to-v9.md	Creates Material UI v9 migration guide (incorrect path)
docs/data/material/migration/upgrade-to-v7/*.md	Updates codemod commands to use @next tag
docs/data/material/integrations/styled-components/styled-components.md	Updates package resolution examples to use @next tag
docs/data/material/getting-started/templates/*/README.md	Updates demo URLs to next.mui.com
docs/data/material/getting-started/support/support.md	Adds v9.0.0 to supported versions table
docs/data/material/getting-started/installation/installation.md	Updates install commands to use @next tag
docs/data/material/components/number-field/number-field.md	Removes npm-tag-reference comment
docs/data/material/components/material-icons/material-icons.md	Updates install commands to use @next tag
docs/data/material/components/icons/icons.md	Updates install commands to use @next tag
docs/data/material/components/about-the-lab/about-the-lab.md	Updates install commands to use @next tag
README.md	Updates logo and homepage URL to next.mui.com

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Netlify deploy preview

• docs/data/material/migration/upgrade-to-v9/upgrade-to-v9.md
• docs/data/system/migration/upgrade-to-v9/upgrade-to-v9.md
• docs/data/material/components/about-the-lab/about-the-lab.md
• docs/data/material/components/icons/icons.md
• docs/data/material/components/material-icons/material-icons.md

Bundle size report

Bundle	Parsed size	Gzip size
@mui/material	0B(0.00%)	🔺+1B(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 9aeba46

[siriwatknp]

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