OCaml evaluator for page dispatch + handler aser, 83/83 Playwright tests

Major architectural change: page function dispatch and handler execution
now go through the OCaml kernel instead of the Python bootstrapped evaluator.

OCaml integration:
- Page dispatch: bridge.eval() evaluates SX URL expressions (geography, marshes, etc.)
- Handler aser: bridge.aser() serializes handler responses as SX wire format
- _ensure_components loads all .sx files into OCaml kernel (spec, web adapter, handlers)
- defhandler/defpage registered as no-op special forms so handler files load
- helper IO primitive dispatches to Python page helpers + IO handlers
- ok-raw response format for SX wire format (no double-escaping)
- Natural list serialization in eval (no (list ...) wrapper)
- Clean pipe: _read_until_ok always sends io-response on error

SX adapter (aser):
- scope-emit!/scope-peek aliases to avoid CEK special form conflict
- aser-fragment/aser-call: strings starting with "(" pass through unserialized
- Registered cond-scheme?, is-else-clause?, primitive?, get-primitive in kernel
- random-int, parse-int as kernel primitives; json-encode, into via IO bridge

Handler migration:
- All IO calls converted to (helper "name" args...) pattern
- request-arg, request-form, state-get, state-set!, now, component-source etc.
- Fixed bare (effect ...) in island bodies leaking disposer functions as text
- Fixed lower-case → lower, ~search-results → ~examples/search-results

Reactive islands:
- sx-hydrate-islands called after client-side navigation swap
- force-dispose-islands-in for outerHTML swaps (clears hydration markers)
- clear-processed! platform primitive for re-hydration

Content restructuring:
- Design, event bridge, named stores, phase 2 consolidated into reactive overview
- Marshes split into overview + 5 example sub-pages
- Nav links use sx-get/sx-target for client-side navigation

Playwright test suite (sx/tests/test_demos.py):
- 83 tests covering hypermedia demos, reactive islands, marshes, spec explorer
- Server-side rendering, handler interactions, island hydration, navigation

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

web/orchestration.sx

@@ -291,8 +291,12 @@
                     (content (if select-sel
                                (select-from-container container select-sel)
                                (children-to-fragment container))))
-                ;; Dispose old islands before swap
-                (dispose-islands-in target)
+                ;; Dispose old islands before swap.
+                ;; outerHTML replaces the target entirely — force-dispose all islands.
+                ;; Other swap styles (innerHTML, beforeend, etc.) may preserve islands.
+                (if (= swap-style "outerHTML")
+                  (force-dispose-islands-in target)
+                  (dispose-islands-in target))
                 ;; Swap
                 (with-transition use-transition
                   (fn ()
@@ -456,6 +460,7 @@
 (define post-swap :effects [mutation io]
   (fn (root)
     ;; Run lifecycle after swap: activate scripts, process SX, hydrate, process
+    (log-info (str "post-swap: root=" (if root (dom-tag-name root) "nil")))
     (activate-scripts root)
     (sx-process-scripts root)
     (sx-hydrate root)
@@ -871,6 +876,7 @@
       (hoist-head-elements-full target)
       (process-elements target)
       (sx-hydrate-elements target)
+      (sx-hydrate-islands target)
       (run-post-render-hooks)
       (dom-dispatch target "sx:clientRoute"
         (dict "pathname" pathname))