Stop recrawling node_modules on every Vite config resolution
The config hook of fumadocs-mdx/vite walked the dependency tree below Fumadocs packages once per chain reaching a package, so a docs app with a few Fumadocs packages read ~10k package.json files (~0.9s) each time Vite resolved its config, which it does once per build environment.
The crawl now visits each package once, breadth-first, and still records the shortest chain to every CommonJS dependency (fumadocs-ui > @base-ui/react > use-sync-external-store/shim and friends). The result is memoized for the process until the package manager's install state changes, so a build with several environments crawls once.