Add s-expression wire format support and test detail view

- HTMX beforeSwap hook intercepts text/sexp responses and renders
  them client-side via sexp.js before HTMX swaps the result in
- sexp_response() helper for returning text/sexp from route handlers
- Test detail page (/test/<nodeid>) with clickable test names
- HTMX navigation to detail returns sexp wire format (4x smaller
  than pre-rendered HTML), full page loads render server-side
- ~test-detail component with back link, outcome badge, and
  error traceback display

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

shared/static/scripts/sexp.js

@@ -1261,6 +1261,18 @@
       Sexp.processScripts(e.detail.target);
       Sexp.hydrate(e.detail.target);
     });
+
+    // S-expression wire format: intercept text/sexp responses and render to HTML
+    // before HTMX swaps them in.  Server sends Content-Type: text/sexp with
+    // s-expression body; sexp.js renders to HTML string for HTMX to swap.
+    document.addEventListener("htmx:beforeSwap", function (e) {
+      var xhr = e.detail.xhr;
+      var ct = xhr.getResponseHeader("Content-Type") || "";
+      if (ct.indexOf("text/sexp") === -1) return;
+      // Render s-expression response to HTML string
+      var html = Sexp.renderToString(xhr.responseText);
+      e.detail.serverResponse = html;
+    });
   }
 
 })(typeof window !== "undefined" ? window : this);