OCaml CEK machine compiled to WebAssembly for browser execution

- wasm_of_ocaml compiles OCaml SX engine to WASM (722/722 spec tests)
- js_of_ocaml fallback also working (722/722 spec tests)
- Thin JS platform layer (sx-platform.js) with ~80 DOM/browser natives
- Lambda callback bridge: SX lambdas callable from JS via handle table
- Side-channel pattern bypasses js_of_ocaml return-value property stripping
- Web adapters (signals, deps, router, adapter-html) load as SX source
- Render mode dispatch: HTML tags + fragments route to OCaml renderer
- Island/component accessors handle both Component and Island types
- Dict-based signal support (signals.sx creates dicts, not native Signal)
- Scope stack implementation (collect!/collected/emit!/emitted/context)
- Bundle script embeds web adapters + WASM loader + platform layer
- SX_USE_WASM env var toggles WASM engine in dev/production
- Bootstrap extended: --web flag transpiles web adapters, :effects stripping

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

shared/sx/templates/shell.sx

@@ -16,6 +16,7 @@
                                (component-hash :as string?) (component-defs :as string?)
                                (pages-sx :as string?) (page-sx :as string?)
                                (asset-url :as string) (sx-js-hash :as string) (body-js-hash :as string?)
+                               (sx-js-file :as string?)
                                (head-scripts :as list?) (inline-css :as string?) (inline-head-js :as string?)
                                (init-sx :as string?) (body-scripts :as list?))
   (<>
@@ -74,7 +75,7 @@ details.group{overflow:hidden}details.group>summary{list-style:none}details.grou
           (raw! (or pages-sx "")))
         (script :type "text/sx" :data-mount "body"
           (raw! (or page-sx "")))
-        (script :src (str asset-url "/scripts/sx-browser.js?v=" sx-js-hash))
+        (script :src (str asset-url "/scripts/" (or sx-js-file "sx-browser.js") "?v=" sx-js-hash))
         ;; Body scripts — configurable per app
         ;; Pass a list (even empty) to override defaults; nil = use defaults
         (if (not (nil? body-scripts))