fix(@langchain/classic): add langsmith as external dependency

[Christian Bromann (christian-bromann)]

Problem

Rolldown is bundling langsmith and eventemitter3 into dist/node_modules despite unbundle: true because:

• langsmith is dynamically imported (await import("langsmith")) in hub/base.ts
• Rolldown resolves dynamic imports during the build and may bundle them even with unbundle: true
• eventemitter3 is bundled as a dependency of langsmith

Solution

Added external: ["langsmith", "eventemitter3"] to the tsdown config to explicitly mark them as external. This ensures:

• They are not bundled into the dist folder
• They remain as runtime dependencies that must be installed separately
• Dynamic imports work correctly at runtime

[changeset-bot]

🦋 Changeset detected

Latest commit: 8ce28a6

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@langchain/classic	Patch
@langchain/community	Patch

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