Kiwix integration: ZIM processor, dashboard tab, wiki.echo6.co citations

- ZIM processor: extract articles from ZIM files, feed into existing enrichment pipeline
- Dashboard: Kiwix tab with library table, ingest toggle, upload, remove
- kiwix-serve on port 8430, wiki.echo6.co behind Authentik
- Citation URLs point to wiki.echo6.co/{zimname}/{article_path}
- Dashboard shows WIKI type badge for ZIM-sourced content
- Appropedia EN (19,445 articles) fully ingested as proof of concept

templates/base.html

@@ -19,6 +19,7 @@
 <div class="nav-domain">
     <a href="/"{% if domain == 'knowledge' %} class="active"{% endif %}>Knowledge</a>
     <a href="/peertube"{% if domain == 'peertube' %} class="active"{% endif %}>PeerTube</a>
+    <a href="/kiwix"{% if domain == 'kiwix' %} class="active"{% endif %}>Kiwix</a>
     <a href="/search"{% if domain == 'search' %} class="active"{% endif %}>Search</a>
     <a href="/settings/keys"{% if domain == 'settings' %} class="active"{% endif %}>Settings</a>
 </div>