Add read-only web UI

Serves Pete's classified-story archive over HTTP alongside the Matrix
bot. Three sections (gaming/tech/politics), Animal-Crossing-vibe Tailwind
templates, day/night palette driven by the visitor's browser clock.
Web port configurable via web.listen_addr and ${PETE_WEB_PORT} in
docker-compose. Tailwind built in a node stage in the Dockerfile so
deployments don't need node at runtime.

internal/web/templates/_card.html

@@ -0,0 +1,25 @@
+{{define "card"}}
+<a href="{{.Story.ArticleURL}}" target="_blank" rel="noopener noreferrer"
+   class="group block rounded-3xl bg-[color:var(--card)] border-2 border-[color:var(--ink)]/10 shadow-pete overflow-hidden hover:-translate-y-1 hover:shadow-pete-lg transition">
+  {{if .Story.ImageURL}}
+  <div class="aspect-[16/10] w-full overflow-hidden bg-[color:var(--ink)]/5">
+    <img src="{{.Story.ImageURL}}" alt="" loading="lazy"
+         class="h-full w-full object-cover group-hover:scale-105 transition duration-500">
+  </div>
+  {{end}}
+  <div class="p-4 space-y-2">
+    <div class="flex items-center gap-2 text-xs">
+      <span class="inline-flex items-center rounded-full bg-theme-{{.Theme}} text-white px-2.5 py-0.5 font-semibold uppercase tracking-wider">
+        {{.Story.Source}}
+      </span>
+      <span class="text-[color:var(--ink)]/50">{{timeAgo .Story.SeenAt}}</span>
+    </div>
+    <h3 class="font-display text-lg font-semibold leading-snug group-hover:underline underline-offset-2 decoration-theme-{{.Theme}}">
+      {{.Story.Headline}}
+    </h3>
+    {{if .Story.Lede}}
+    <p class="text-sm text-[color:var(--ink)]/70 line-clamp-3">{{.Story.Lede}}</p>
+    {{end}}
+  </div>
+</a>
+{{end}}