fix(menu-button): close behavior and ensure menu overlays

[heloiselui]

Closes #21159
Closes #20349

This PR fixes cds-menu-button/cds-menu back in line with React so menus close when they should and stay on top of nearby content.

Changelog

New

• None

Changed

• All trigger clicks, blurs, and Escape presses now flow through _closeMenu, so the same focus-restoration rules apply for every close path.
• cds-menu listens for ${prefix}-menu-close-root-request from menu items, resets its placement when open flips, and passes the original trigger event through ${prefix}-menu-closed.
• Menu items dispatch the new close request when activated, matching React
• Raised the menu host to Carbon’s modal z-index so the overlay doesn’t hide behind nearby content.
• Update snap

Removed

• Dropped the dead @query(${prefix}-menu) since the menu lives in the light DOM slot.

Testing / Reviewing

• Go to WC Deploy Preview > Menu Button
• Open and close the menu button should open/close.
• Press Escape menu should closes and focuses the trigger.
• Scroll while open and confirm the menu stays aligned in the overview page.

PR Checklist

As the author of this PR, before marking ready for review, confirm you:

• Reviewed every line of the diff
• [ ] Updated documentation and storybook examples
• [ ] Wrote passing tests that cover this change
• [ ] Addressed any impact on accessibility (a11y)
• Tested for cross-browser consistency
• Validated that this code is ready for review and status checks should pass

More details can be found in the pull request guide

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[codecov]

Codecov Report

❌ Patch coverage is 71.94245% with 39 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.08%. Comparing base (6c5d4d0) to head (c5b74b7).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...mponents/src/components/menu-button/menu-button.ts	59.30%	34 Missing and 1 partial ⚠️
...es/web-components/src/components/menu/menu-item.ts	87.50%	2 Missing ⚠️
...ackages/web-components/src/components/menu/menu.ts	94.59%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #21184      +/-   ##
==========================================
- Coverage   85.17%   85.08%   -0.10%     
==========================================
  Files         530      530              
  Lines       40889    41015     +126     
  Branches     6280     6350      +70     
==========================================
+ Hits        34829    34898      +69     
- Misses       5900     5955      +55     
- Partials      160      162       +2     

Flag	Coverage Δ
main-packages	85.72% <ø> (ø)
web-components	84.72% <71.94%> (-0.10%)	⬇️

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[maradwan26]

LGTM!