frontend-foundation: GOAT front-end Phase 1 — auth, tag management, public tag page (22/22 spec scenarios pass)

frontend/templates/not-found.html

@@ -0,0 +1,8 @@
+{{define "content"}}
+<div class="mx-auto max-w-md text-center">
+  <div class="text-5xl">🔎</div>
+  <h1 class="mt-4 text-2xl font-bold">Tag not found</h1>
+  <p class="mt-2 text-stone-600">We couldn't find a WhereWoof tag with that code. Check the code on the tag and try again.</p>
+  <a href="/" class="mt-6 inline-block rounded bg-stone-900 px-4 py-2 text-sm font-semibold text-white hover:bg-stone-700">Go home</a>
+</div>
+{{end}}