SXC content: docs/examples/home/reference pages + SX testing runner

New sxc/ content tree with 120 page files across docs, examples, home,
and reference demos. sx/sx/testing/ adds page-runner.sx (317L) and
index-runner.sx (394L) — SX-native test runner pages for
browser-based evaluation.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

sx/sxc/examples/bulk-update-demo.sx

@@ -0,0 +1,44 @@
+(defcomp
+  (&key users)
+  (div
+    (~tw :tokens "space-y-3")
+    (form
+      :id "bulk-form"
+      (div
+        (~tw :tokens "flex gap-2 mb-3")
+        (button
+          :type "button"
+          :sx-post "/sx/(geography.(hypermedia.(example.(api.bulk))))?action=activate"
+          :sx-target "#bulk-table"
+          :sx-swap "innerHTML"
+          :sx-include "#bulk-form"
+          (~tw :tokens "px-3 py-1.5 bg-emerald-600 text-white rounded text-sm hover:bg-emerald-700")
+          "Activate")
+        (button
+          :type "button"
+          :sx-post "/sx/(geography.(hypermedia.(example.(api.bulk))))?action=deactivate"
+          :sx-target "#bulk-table"
+          :sx-swap "innerHTML"
+          :sx-include "#bulk-form"
+          (~tw :tokens "px-3 py-1.5 bg-stone-600 text-white rounded text-sm hover:bg-stone-700")
+          "Deactivate"))
+      (table
+        (~tw :tokens "w-full text-left text-sm")
+        (thead
+          (tr
+            (~tw :tokens "border-b border-stone-200")
+            (th (~tw :tokens "px-3 py-2 w-8") "")
+            (th (~tw :tokens "px-3 py-2 font-medium text-stone-600") "Name")
+            (th (~tw :tokens "px-3 py-2 font-medium text-stone-600") "Email")
+            (th (~tw :tokens "px-3 py-2 font-medium text-stone-600") "Status")))
+        (tbody
+          :id "bulk-table"
+          (map
+            (fn
+              (u)
+              (~examples/bulk-row
+                :id (nth u 0)
+                :name (nth u 1)
+                :email (nth u 2)
+                :status (nth u 3)))
+            users))))))