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>

hosts/ocaml/browser/sx-platform.js

@@ -166,6 +166,22 @@
     document.cookie = args[0] + "=" + encodeURIComponent(args[1] || "") + ";path=/;max-age=31536000;SameSite=Lax";
   });
 
+  // IntersectionObserver — native JS to avoid bytecode callback issues
+  K.registerNative("observe-intersection", function(args) {
+    var el = args[0], callback = args[1], once = args[2], delay = args[3];
+    var obs = new IntersectionObserver(function(entries) {
+      for (var i = 0; i < entries.length; i++) {
+        if (entries[i].isIntersecting) {
+          var d = (delay && delay !== null) ? delay : 0;
+          setTimeout(function() { K.callFn(callback, []); }, d);
+          if (once) obs.unobserve(el);
+        }
+      }
+    });
+    obs.observe(el);
+    return obs;
+  });
+
   // ================================================================
   // Load SX web libraries and adapters
   // ================================================================

web/boot.sx

@@ -321,7 +321,7 @@
                 (dom-set-text-content el "")
                 (dom-append el body-dom)
                 (dom-set-data el "sx-disposers" disposers)
-                (process-elements el)
+                (set-timeout (fn () (process-elements el)) 0)
                 (log-info
                   (str
                     "hydrated island: "
@@ -430,7 +430,7 @@
       (sx-hydrate-elements nil)
       (sx-hydrate-islands nil)
       (run-post-render-hooks)
-      (process-elements nil)
+      (set-timeout (fn () (process-elements nil)) 0)
       (dom-listen (dom-window) "popstate" (fn (e) (handle-popstate 0)))
       (dom-set-attr
         (host-get (dom-document) "documentElement")

web/lib/boot-helpers.sx

@@ -430,17 +430,6 @@
         (host-callback thunk))
       (thunk))))
 
-(define
-  observe-intersection
-  (fn
-    (el callback once? delay)
-    (let
-      ((cb (host-callback (fn (entries) (for-each (fn (entry) (when (host-get entry "isIntersecting") (if delay (set-timeout (fn () (callback entry)) delay) (callback entry)) (when once? (host-call observer "unobserve" el)))) (host-call entries "forEach" (host-callback (fn (e) e))))))))
-      (let
-        ((observer (host-new "IntersectionObserver" (host-callback (fn (entries) (let ((arr-len (host-get entries "length"))) (let loop ((i 0)) (when (< i arr-len) (let ((entry (host-call entries "item" i))) (when (and entry (host-get entry "isIntersecting")) (if delay (set-timeout (fn () (callback entry)) delay) (callback entry)) (when once? (host-call observer "unobserve" el)))) (loop (+ i 1))))))))))
-        (host-call observer "observe" el)
-        observer))))
-
 (define
   event-source-connect
   (fn

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)