Plugins: add root-alias shim and cache/docs updates

scripts/copy-plugin-sdk-root-alias.mjs

@@ -0,0 +1,10 @@
+#!/usr/bin/env node
+
+import { copyFileSync, mkdirSync } from "node:fs";
+import { dirname, resolve } from "node:path";
+
+const source = resolve("src/plugin-sdk/root-alias.cjs");
+const target = resolve("dist/plugin-sdk/root-alias.cjs");
+
+mkdirSync(dirname(target), { recursive: true });
+copyFileSync(source, target);