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/inline-edit-form.sx

@@ -0,0 +1,25 @@
+(defcomp
+  (&key value)
+  (form
+    :sx-post "/sx/(geography.(hypermedia.(example.(api.edit))))"
+    :sx-target "#edit-target"
+    :sx-swap "innerHTML"
+    (~tw :tokens "flex items-center gap-2 p-3 rounded border border-violet-300 bg-violet-50")
+    (input
+      :type "text"
+      :name "value"
+      :value value
+      (~tw :tokens "flex-1 px-3 py-1.5 border border-stone-300 rounded text-sm focus:outline-none focus:ring-2 focus:ring-violet-500"))
+    (button
+      :type "submit"
+      (~tw :tokens "px-3 py-1.5 bg-violet-600 text-white rounded text-sm hover:bg-violet-700")
+      "save")
+    (button
+      :type "button"
+      :sx-get (str
+        "/sx/(geography.(hypermedia.(example.(api.edit-cancel))))?value="
+        value)
+      :sx-target "#edit-target"
+      :sx-swap "innerHTML"
+      (~tw :tokens "px-3 py-1.5 bg-stone-200 text-stone-700 rounded text-sm hover:bg-stone-300")
+      "cancel")))