Uncommitted sx-tools changes: WASM bundles, Playwright specs, engine fixes

WASM browser bundles rebuilt with latest kernel. Playwright test specs
updated (helpers, navigation, handler-responses, hypermedia-handlers,
isomorphic, SPA navigation). Engine/boot/orchestration SX files updated.
Handler examples and not-found page refreshed.

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

web/boot.sx

@@ -433,15 +433,6 @@
       (run-post-render-hooks)
       (flush-collected-styles)
       (set-timeout (fn () (process-elements nil)) 0)
-      (dom-listen
-        (dom-window)
-        "popstate"
-        (fn
-          (e)
-          (let
-            ((state (host-get e "state"))
-              (scrollY (if state (or (dict-get state "scrollY") 0) 0)))
-            (handle-popstate scrollY))))
       (dom-set-attr
         (host-get (dom-document) "documentElement")
         "data-sx-ready"