fix(bitcoin-ui): vendor Tailwind CSS — drop cdn.tailwindcss.com

The Bitcoin UI loaded the Tailwind Play CDN at runtime: unstyled on
offline nodes + a production console warning. Replaced with a
hand-extracted static stylesheet (~125 utilities actually used, same
approach as lnd-ui), served from the container. podman build + runtime
smoke test verified (GET /tailwind.css 200, zero cdn references).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docker/bitcoin-ui/index.html

@@ -7,7 +7,7 @@
     <meta http-equiv="Pragma" content="no-cache">
     <meta http-equiv="Expires" content="0">
     <title id="pageTitle">Bitcoin Node - Archipelago</title>
-    <script src="https://cdn.tailwindcss.com"></script>
+    <link rel="stylesheet" href="/tailwind.css">
     <style>
         * {
             margin: 0;