Add Breadcrumb component

## Summary

Add a **Breadcrumb** component to the MUI Base UI library. This component would provide a lightweight, unstyled primitive for building breadcrumb navigation patterns, allowing developers to implement consistent navigation hierarchies across applications.

## Examples in other libraries

- [Radix UI – Breadcrumbs (community implementations)](https://www.radix-ui.com/)
- [Chakra UI – Breadcrumb](https://chakra-ui.com/docs/components/breadcrumb)
- [Ant Design – Breadcrumb](https://ant.design/components/breadcrumb/)

These libraries provide flexible breadcrumb primitives that can be styled or extended, serving as good references for API design and accessibility considerations.

## Motivation

Breadcrumbs are a common navigation pattern in modern web applications, especially for:
- **Hierarchical navigation**: Allowing users to understand their current location within nested routes or sections.
- **Improved UX**: Providing quick access to higher-level pages without relying solely on back buttons or menus.
- **Accessibility**: Offering screen reader–friendly navigation landmarks.

Currently, MUI Base UI does not include a breadcrumb primitive, which means developers must either:
- Rebuild this pattern from scratch, or
- Depend on higher-level libraries that may not align with the unstyled, headless philosophy of Base UI.

Adding a Breadcrumb component would:
- Improve **developer productivity** by providing a ready-to-use, accessible primitive.
- Ensure **consistency** across projects using MUI Base UI.
- Align with the library’s goal of offering unstyled building blocks for common UI patterns.