Update dependency typedoc-plugin-markdown to v4.9.0 (#1409)

This PR contains the following updates:

| Package | Change | Age | Confidence |
|---|---|---|---|
| [typedoc-plugin-markdown](https://typedoc-plugin-markdown.org)
([source](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/tree/HEAD/packages/typedoc-plugin-markdown))
| [`4.8.1` ->
`4.9.0`](https://renovatebot.com/diffs/npm/typedoc-plugin-markdown/4.8.1/4.9.0)
|
[![age](https://developer.mend.io/api/mc/badges/age/npm/typedoc-plugin-markdown/4.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/typedoc-plugin-markdown/4.8.1/4.9.0?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>typedoc2md/typedoc-plugin-markdown
(typedoc-plugin-markdown)</summary>

###
[`v4.9.0`](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/blob/HEAD/packages/typedoc-plugin-markdown/CHANGELOG.md#490-2025-09-19)

[Compare
Source](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/compare/[email protected]@4.9.0)

##### Minor Changes

- Exposed new option `navigationJson` that can be used to write
navigation structure as JSON to disk.

##### Patch Changes

- Remove type params from inline reflection titles when router=module to
resolve anchoring issues
([#&#8203;843](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/issues/843)).

</details>

---

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