Add Heavy Dependencies to a Lightweight DSH Web Plugin

A lightweight Web plugin (small client bundle, no build farm) can still ship a multi-megabyte renderer — if the heavy code never loads until it is needed and degrades gracefully when it cannot load. This skill is the integration checklist; every item below was earned from a real mermaid integration.

1. Decide lazy vs inline

If the dependency would multiply the client bundle several-fold and only one feature needs it (a fence renderer, an editor opened on demand), do NOT inline it into the client bundle. Split it into a separate chunk file the client imports dynamically only when the feature actually renders.

2. Bundle the chunk as ONE file