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.

config.example.yaml

@@ -30,6 +30,12 @@ storage:
   recent_window_hours: 24
   classification_log_days: 7
 
+web:
+  enabled: true
+  listen_addr: ":8080"
+  site_title: "Pete"
+  base_url: "https://news.parodia.dev"
+
 sources:
   - name: "The Guardian — World"
     feed_url: "https://www.theguardian.com/world/rss"