Move example CSS to basics.css, pretty-print wire response, update sx logo

- Move .sx-fade-in and .sx-loading-btn CSS from inline (style) tags to
  basics.css so they go through the on-demand CSS registry
- Pretty-print sx source in wire response display (not all on one line)
- Change sx logo from </> icon to (</>) text

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/static/styles/basics.css

@@ -30,3 +30,22 @@
 :where(h1, h2, h3, h4, h5, h6) {
     font-weight: 800;
 }
+
+/* sx example demos — on-demand CSS for interactive examples */
+@keyframes sxFadeIn {
+    from { opacity: 0; transform: translateY(8px); }
+    to { opacity: 1; transform: translateY(0); }
+}
+.sx-fade-in {
+    animation: sxFadeIn 0.5s ease-out;
+}
+.sx-loading-btn.sx-request {
+    opacity: 0.7;
+    pointer-events: none;
+}
+.sx-loading-btn.sx-request .sx-spinner {
+    display: inline-block;
+}
+.sx-loading-btn .sx-spinner {
+    display: none;
+}