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/reference/ref-ignore-demo.sx

@@ -0,0 +1,26 @@
+(defcomp
+  ()
+  (div
+    (~tw :tokens "space-y-3")
+    (button
+      :sx-get "/sx/(geography.(hypermedia.(reference.(api.time))))"
+      :sx-target "#ref-ignore-container"
+      :sx-swap "innerHTML"
+      (~tw :tokens "px-4 py-2 bg-violet-600 text-white rounded hover:bg-violet-700 transition-colors text-sm")
+      "Swap container")
+    (div
+      :id "ref-ignore-container"
+      (~tw :tokens "space-y-2")
+      (div
+        :sx-ignore "true"
+        (~tw :tokens "p-2 bg-amber-50 rounded border border-amber-200")
+        (p
+          (~tw :tokens "text-sm text-amber-800")
+          "This subtree has sx-ignore — it won't change.")
+        (input
+          :type "text"
+          :placeholder "Type here — ignored during swap"
+          (~tw :tokens "mt-1 w-full px-2 py-1 border border-amber-300 rounded text-sm")))
+      (div
+        (~tw :tokens "p-2 bg-stone-100 rounded text-sm text-stone-600")
+        "This text WILL be replaced on swap."))))