docs: bundle assets with Hugo

Also:

* load any docs' third-party dependencies from node_modules (except for examples)
* exclude docsearch from layouts that don't use it
* preconnect to algolia only when not examples layout
* switch to `RelPermalink`
* refactor JS assets into partials

site/assets/js/partials/sidebar.js

@@ -0,0 +1,30 @@
+// NOTICE!! DO NOT USE ANY OF THIS JAVASCRIPT
+// IT'S ALL JUST JUNK FOR OUR DOCS!
+// ++++++++++++++++++++++++++++++++++++++++++
+
+/*
+ * JavaScript for Bootstrap's docs (https://getbootstrap.com/)
+ * Copyright 2011-2024 The Bootstrap Authors
+ * Licensed under the Creative Commons Attribution 3.0 Unported License.
+ * For details, see https://creativecommons.org/licenses/by/3.0/.
+ */
+
+export default () => {
+  // Scroll the active sidebar link into view
+  const sidenav = document.querySelector('.bd-sidebar')
+  const sidenavActiveLink = document.querySelector('.bd-links-nav .active')
+
+  if (!sidenav || !sidenavActiveLink) {
+    return
+  }
+
+  const sidenavHeight = sidenav.clientHeight
+  const sidenavActiveLinkTop = sidenavActiveLink.offsetTop
+  const sidenavActiveLinkHeight = sidenavActiveLink.clientHeight
+  const viewportTop = sidenavActiveLinkTop
+  const viewportBottom = viewportTop - sidenavHeight + sidenavActiveLinkHeight
+
+  if (sidenav.scrollTop > viewportTop || sidenav.scrollTop < viewportBottom) {
+    sidenav.scrollTop = viewportTop - (sidenavHeight / 2) + (sidenavActiveLinkHeight / 2)
+  }
+}