Restore hyperscript work on stable site base (908f4f80)

Reset to last known-good state (908f4f80) where links, stepper, and
islands all work, then recovered all hyperscript implementation,
conformance tests, behavioral tests, Playwright specs, site sandbox,
IO-aware server loading, and upstream test suite from f271c88a.

Excludes runtime changes (VM resolve hook, VmSuspended browser handler,
sx_ref.ml guard recovery) that need careful re-integration.

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

shared/static/wasm/sx/orchestration.sx

@@ -6,9 +6,6 @@
 (import (web adapter-dom))
 (import (web engine))
 
-(import (hyperscript integration)) ;; end define-library
-
-;; Re-export to global namespace for backward compatibility
 (define-library
   (web orchestration)
   (export
@@ -629,8 +626,7 @@
         (sx-hydrate-islands root)
         (run-post-render-hooks)
         (flush-collected-styles)
-        (process-elements root)
-        (hs-boot-subtree! root)))
+        (process-elements root)))
     (define
       process-settle-hooks
       :effects (mutation io)
@@ -1636,6 +1632,7 @@
         (do
           (sx-process-scripts nil)
           (sx-hydrate nil)
-          (process-elements nil))))))
+          (process-elements nil)))))) ;; end define-library
 
+;; Re-export to global namespace for backward compatibility
 (import (web orchestration))