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/dialog-modal.sx

@@ -0,0 +1,27 @@
+(defcomp
+  (&key title message)
+  (div
+    (~tw :tokens "fixed inset-0 z-50 flex items-center justify-center")
+    (div
+      (~tw :tokens "absolute inset-0 bg-black/50")
+      :sx-get "/sx/(geography.(hypermedia.(example.(api.dialog-close))))"
+      :sx-target "#dialog-container"
+      :sx-swap "innerHTML")
+    (div
+      (~tw :tokens "relative bg-stone-100 rounded-lg shadow-xl p-6 max-w-md w-full mx-4 space-y-4")
+      (h3 (~tw :tokens "text-lg font-semibold text-stone-800") title)
+      (p (~tw :tokens "text-stone-600") message)
+      (div
+        (~tw :tokens "flex justify-end gap-2")
+        (button
+          :sx-get "/sx/(geography.(hypermedia.(example.(api.dialog-close))))"
+          :sx-target "#dialog-container"
+          :sx-swap "innerHTML"
+          (~tw :tokens "px-4 py-2 bg-stone-200 text-stone-700 rounded text-sm hover:bg-stone-300")
+          "Cancel")
+        (button
+          :sx-get "/sx/(geography.(hypermedia.(example.(api.dialog-close))))"
+          :sx-target "#dialog-container"
+          :sx-swap "innerHTML"
+          (~tw :tokens "px-4 py-2 bg-violet-600 text-white rounded text-sm hover:bg-violet-700")
+          "Confirm")))))