Fix infinite scroll and all sx-trigger/sx-get element binding

Root cause: process-elements during WASM boot-init marks elements as
processed but process-one silently fails (effect functions don't execute
in WASM boot context). Deferred process-elements then skips them.

Fixes:
- boot-init: defer process-elements via set-timeout 0
- hydrate-island: defer process-elements via set-timeout 0
- process-elements: move mark-processed! after process-one so failed
  boot-context calls don't poison the flag
- observe-intersection: native JS platform function (K.registerNative)
  to avoid bytecode callback issue with IntersectionObserver
- Remove SX observe-intersection from boot-helpers.sx (was overriding
  the working native version)

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

web/orchestration.sx

@@ -428,7 +428,7 @@
               (observe-intersection
                 el
                 (fn () (execute-request el nil nil))
-                false
+                true
                 (get mods "delay"))
               (= kind "load")
               (set-timeout
@@ -438,7 +438,7 @@
               (observe-intersection
                 el
                 (fn () (execute-request el nil nil))
-                true
+                false
                 (get mods "delay"))
               (= kind "event")
               (bind-event el (get trigger "event") mods verbInfo))))
@@ -1484,8 +1484,8 @@
           (el)
           (when
             (not (is-processed? el "verb"))
-            (mark-processed! el "verb")
-            (process-one el)))
+            (process-one el)
+            (mark-processed! el "verb")))
         els))
     (process-boosted root)
     (process-sse root)