chore(deps): bump langchain from 0.3.18 to 0.3.19 in the langchain group (#1366)

Bumps the langchain group with 1 update: [langchain](https://github.com/langchain-ai/langchainjs).


Updates `langchain` from 0.3.18 to 0.3.19
- [Release notes](https://github.com/langchain-ai/langchainjs/releases)
- [Changelog](https://github.com/langchain-ai/langchainjs/blob/main/release_workspace.js)
- [Commits](langchain-ai/langchainjs@0.3.18...0.3.19)

---
updated-dependencies:
- dependency-name: langchain
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: langchain
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -47,7 +47,7 @@
     "gpt-tokenizer": "2.8.1",
     "he": "1.2.0",
     "jotai": "2.12.0",
-    "langchain": "0.3.18",
+    "langchain": "0.3.19",
     "markdown-to-txt": "2.0.1",
     "nanoid": "5.0.9",
     "next": "15.1.7",