SPA navigation, page component refactors, WASM rebuild

Refactor page components (docs, examples, specs, reference, layouts)
and adapters (adapter-sx, boot-helpers, orchestration) across sx/ and
web/ directories. Add Playwright SPA navigation tests. Rebuild WASM
kernel with updated bytecode. Add OCaml primitives for request handling.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

sx/sx/not-found.sx

@@ -1,19 +1,20 @@
-;; 404 Not Found page content
-
-(defcomp ~not-found/content (&key (path :as string?))
-  (div :class "max-w-3xl mx-auto px-4 py-12 text-center"
-    (h1 :style (tw "text-stone-800 text-3xl font-bold")
-      "404")
-    (p :class "mt-4"
-       :style (tw "text-stone-500 text-lg")
-      "Page not found")
-    (when path
-      (p :class "mt-2"
-         :style (tw "text-stone-400 text-sm font-mono")
-        path))
-    (a :href "/sx/"
-       :sx-get "/sx/" :sx-target "#main-panel" :sx-select "#main-panel"
-       :sx-swap "outerHTML" :sx-push-url "true"
-       :class "inline-block mt-6 px-4 py-2 rounded border transition-colors"
-       :style (tw "text-violet-700 text-sm border-violet-200")
+(defcomp
+  ~not-found/content
+  (&key (path :as string?))
+  (div
+    :class "max-w-3xl mx-auto px-4 py-12 text-center"
+    (h1 :style (tw "text-stone-800 text-3xl font-bold") "404")
+    (p :class "mt-4" :style (tw "text-stone-500 text-lg") "Page not found")
+    (when
+      path
+      (p :class "mt-2" :style (tw "text-stone-400 text-sm font-mono") path))
+    (a
+      :href "/sx/"
+      :sx-get "/sx/"
+      :sx-target "#sx-content"
+      :sx-select "#sx-content"
+      :sx-swap "outerHTML"
+      :sx-push-url "true"
+      :class "inline-block mt-6 px-4 py-2 rounded border transition-colors"
+      :style (tw "text-violet-700 text-sm border-violet-200")
       "Back to home")))