feat(headless): add Menu primitive

[alexcarpenter]

Summary

• Adds Menu primitive with nested submenus via FloatingTree
• safePolygon hover zones for submenu navigation
• Combined hover/click triggers, keyboard navigation, Separator support

Review Stack

Review order — start at #8474 (foundation) and work up. Each PR adds one primitive on top of the previous.

#	PR	What it adds	Base
1	#8474	Foundation (infra + hooks + utils + Dialog)	main
2	#8475	Accordion	← #8474
3	#8476	Tabs	← #8475
4	#8477	cssVars + Tooltip	← #8476
5	#8478	Popover	← #8477
6	#8479	Select	← #8478
7	#8480	Menu	← #8479
8	#8481	Autocomplete + integration tests	← #8480

Test plan

• pnpm build succeeds
• pnpm test passes (+31 menu tests)
• CI passes

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Ready	Preview, Comment	May 5, 2026 6:38pm

[changeset-bot]

⚠️ No Changeset found

Latest commit: 734c7b7

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR