[Bug]: sp-menu used within an overlay-trigger breaks a11y and does not close via keyboard escape

### Code of conduct

- [x] I agree to follow this project's code of conduct.

### Impacted component(s)

sp-menu, sp-popover, overlay-trigger

### Library version

1.9.0

### Expected behavior

Desired behavior would be to have overlay-trigger (or sp-popover?)  handle the escape character similar to how sp-picker does when a menu is rendered inside to properly dismiss

### Actual behavior

When using the keyboard items the menu does not close when pressing the escape character. Example of the issue can be found here https://stackblitz.com/edit/vitejs-vite-bx2bvqr8?file=src%2Fmy-element.ts

Apparent root cause and workaround used

Escape was swallowed with no fallback. SWC's OverlayStack defers Escape-to-close to the browser's native popover light-dismiss on supporting browsers (guarded by showPopover support). But a focused sp-menu-item calls preventDefault() on Escape (to support submenu back-out — MenuItem.handleKeydown), which cancels that native dismiss. sp-action-menu/sp-picker don't hit this because Picker has its own explicit Escape handler; a bare overlay-trigger + sp-menu has none, so nothing closes the menu.

### Screenshots

Reproduction here https://stackblitz.com/edit/vitejs-vite-bx2bvqr8?file=src%2Fmy-element.ts

### What browsers are you seeing the problem in?

Chrome

### How can we reproduce this issue?

https://stackblitz.com/edit/vitejs-vite-bx2bvqr8?file=src%2Fmy-element.ts

### Sample code or abstract reproduction which illustrates the problem

Example code here: https://stackblitz.com/edit/vitejs-vite-bx2bvqr8?file=src%2Fmy-element.ts

### Severity

SEV 3

### Logs taken while reproducing problem

_No response_

### Would you like to track this issue in Jira?

- [ ] Yes, please tell me the ticket number!

Start with SWC's OverlayStack and MenuItem.handleKeydown, then reproduce the issue using the linked StackBlitz example in Chrome. Trace how Escape is handled when sp-menu is inside overlay-trigger or sp-popover, and verify that pressing Escape dismisses the menu without breaking submenu keyboard navigation.

Written by the indexing model from the issue text.