Replace Modal with new Dialog component (#41917)

Replace Modal with new Dialog component (#41917)

* Add Dialog component using native HTML dialog element

New component that leverages the native HTML <dialog> element for modals
and non-modal dialogs with built-in backdrop and accessibility support.

Features:
- Modal dialogs using showModal() with automatic backdrop
- Non-modal dialogs using show() for persistent UI elements
- Static backdrop option (prevents close on outside click)
- Keyboard support (Escape to close, focus trapping for modals)
- Smooth open/close animations via CSS
- Events: show, shown, hide, hidden, hidePrevented
- Data API for toggling with data-bs-toggle="dialog"

JavaScript:
- js/src/dialog.js - Main component class
- js/tests/unit/dialog.spec.js - Unit tests
- js/tests/visual/dialog.html - Visual test page

SCSS:
- scss/_dialog.scss - Component styles

Docs:
- Add dialog component documentation
- Update modal docs with dialog references

* Modal examples now Dialog examples, needs improvement

* Remove all of Modal

* real words

* Fix layout while I'm here

* Lint Markdown

* New dialog size options