chore: add a changeset for the build memory work

Assisted-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: ovflowd

.changeset/build-memory.md

@@ -0,0 +1,7 @@
+---
+'@doc-kit/core': minor
+'@doc-kit/generator-react': minor
+'@node-core/doc-kit-legacy': patch
+---
+
+Build with 30–50% less memory, in less than half the time: Shiki registers each language once code in it is highlighted, highlighted code reaches pages as static markup rather than a tree per token, `all.html` is rendered by the worker pool and no longer minified, idle workers end after 500ms, and each worker's heap is limited to 512MB, which Node.js's `--max-old-space-size` raises.