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/index.html

@@ -0,0 +1,44 @@
+{{define "title"}}{{.SiteTitle}} — your news feed{{end}}
+
+{{define "main"}}
+<section class="mt-2 mb-10 sm:mb-14 text-center">
+  <h1 class="font-display text-4xl sm:text-6xl font-bold leading-tight">
+    a friendlier news feed.
+  </h1>
+  <p class="mx-auto mt-3 max-w-xl text-base sm:text-lg text-[color:var(--ink)]/70">
+    Pete reads RSS, sorts stories, and posts them to Matrix.
+    Here's what he's been reading lately.
+  </p>
+</section>
+
+{{range .Sections}}
+<section class="mb-12">
+  <div class="flex items-end justify-between gap-3 mb-4">
+    <div>
+      <h2 class="font-display text-2xl sm:text-3xl font-bold">
+        <span aria-hidden="true">{{.Channel.Emoji}}</span>
+        <a href="/{{.Channel.Slug}}" class="hover:underline underline-offset-4 decoration-theme-{{.Channel.Theme}} decoration-4">
+          {{.Channel.Title}}
+        </a>
+      </h2>
+      <p class="text-sm text-[color:var(--ink)]/60 mt-1">{{.Channel.Blurb}}</p>
+    </div>
+    <a href="/{{.Channel.Slug}}" class="hidden sm:inline-flex items-center gap-1 text-sm font-semibold rounded-full bg-theme-{{.Channel.Theme}} text-white px-4 py-2 shadow-pete hover:-translate-y-0.5 transition">
+      more →
+    </a>
+  </div>
+
+  {{if .Stories}}
+  <div class="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4">
+    {{range .Stories}}
+      {{template "card" dict "Story" . "Theme" $.Channel.Theme}}
+    {{end}}
+  </div>
+  {{else}}
+  <div class="rounded-3xl bg-[color:var(--card)] border-2 border-dashed border-[color:var(--ink)]/15 p-8 text-center text-[color:var(--ink)]/60">
+    Nothing here yet — Pete's still listening.
+  </div>
+  {{end}}
+</section>
+{{end}}
+{{end}}