Fix canonical URL and sitemap trailing slash consistency

app/middleware/trailing-slash.global.ts

@@ -0,0 +1,17 @@
+// The build produces a static site (Nitro's default `autoSubfolderIndex`
+// writes every route as `path/index.html`), and the web server that serves
+// those files 301-redirects a bare directory path to its slash-terminated
+// form. Docus's own canonical/og:url logic (useSeo.ts) just does
+// `joinURL(site.url, route.path)`, with no awareness of that, so any link
+// or bookmark missing the slash renders a canonical tag pointing right back
+// at itself, minus the slash the server then redirects to: a loop that
+// keeps the page out of the index. Redirecting here, before the page ever
+// renders, means `route.path` already carries the slash everywhere that
+// matters (canonical, og:url, hreflang, JSON-LD, the sitemap).
+export default defineNuxtRouteMiddleware((to) => {
+  if (to.path.endsWith('/')) return
+  // Leave actual files (sitemap.xml, favicon.ico, ...) alone.
+  if (to.path.includes('.')) return
+
+  return navigateTo(to.fullPath + '/', { redirectCode: 301 })
+})