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-row.sx

@@ -0,0 +1,17 @@
+(defcomp
+  (&key id name email status)
+  (tr
+    (~tw :tokens "border-b border-stone-100")
+    (td (~tw :tokens "px-3 py-2") (input :type "checkbox" :name "ids" :value id))
+    (td (~tw :tokens "px-3 py-2 text-stone-700") name)
+    (td (~tw :tokens "px-3 py-2 text-stone-700") email)
+    (td
+      (~tw :tokens "px-3 py-2")
+      (span
+        :class (str
+          "px-2 py-0.5 rounded text-xs font-medium "
+          (if
+            (= status "active")
+            "bg-emerald-100 text-emerald-700"
+            "bg-stone-100 text-stone-500"))
+        status))))