## Objective

Add functional horizontal scrollbars to wide Markdown tables, matching
the existing code-block scrollbar pattern.

Fixes #61437

PR was talked about in https://github.com/zed-industries/zed/pull/61698

## Implementation:
- Added a `BTreeMap<usize, ScrollHandle>` to `Markdown` for table scroll
handles, keyed by source-range start.
- During `MarkdownElement` layout, each table container is connected to
a `Scrollbars` widget configured for the horizontal axis, using a stable
ID derived from `("markdown-table-scrollbar", range.start)`.
- The inner table div uses `overflow_x_scroll()` + `track_scroll()` with
`restrict_scroll_to_axis`.
- Handles for removed tables are discarded after re-rendering.
- No public API, setting, schema, or migration changes required.

## Recording


https://github.com/user-attachments/assets/cd0f635b-a485-4de8-9059-40a05f256fb1

## Release Notes:

- Improved navigation of wide Markdown tables with horizontal
scrollbars.

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Co-authored-by: MrSubidubi <finn@zed.dev>