WASM kernel fixes: parse, env sync, iterative CEK, click delegation

Browser kernel:
- Add `parse` native fn (matches server: unwrap single, list for multiple)
- Restore env==global_env guard on _env_bind_hook (let bindings must not
  leak to _vm_globals — caused JIT CSSX "Not callable: nil" errors)
- Add _env_bind_hook call in env_set_id so set! mutations sync to VM globals
- Fire _vm_global_set_hook from OP_DEFINE so VM defines sync back to CEK env

CEK evaluator:
- Replace recursive cek_run with iterative while loop using sx_truthy
  (previous attempt used strict Bool true matching, broke in wasm_of_ocaml)
- Remove dead cek_run_iterative function

Web modules:
- Remove find-matching-route and parse-route-pattern stubs from
  boot-helpers.sx that shadowed real implementations from router.sx
- Sync boot-helpers.sx to dist/static dirs for bytecode compilation

Platform (sx-platform.js):
- Set data-sx-ready attribute after boot completes (was only in boot-init
  which sx-platform.js doesn't call — it steps through boot manually)
- Add document-level click delegation for a[sx-get] links as workaround
  for bytecoded bind-event not attaching per-element listeners (VM closure
  issue under investigation — bind-event runs but dom-add-listener calls
  don't result in addEventListener)

Tests:
- New test_kernel.js: 24 tests covering env sync, parse, route matching,
  host FFI/preventDefault, deep recursion
- New navigation test: "sx-get link fetches SX not HTML and preserves layout"
  (currently catches layout breakage after SPA swap — known issue)

Known remaining issues:
- JIT CSSX failures: closure-captured variables resolve to nil in VM bytecode
- SPA content swap via execute-request breaks page layout
- Bytecoded bind-event doesn't attach per-element addEventListener (root
  cause unknown — when listen-target guard appears to block despite element
  being valid)

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

hosts/ocaml/browser/sx_browser.ml

@@ -216,8 +216,8 @@ let sync_env_to_vm () =
   ) global_env.bindings
 
 (* Hook: intercept env_bind on global_env to also update _vm_globals.
-   This ensures VmClosures see new definitions immediately, even during
-   a single boot-init call that loads page scripts and components. *)
+   Only sync bindings on the global env — let bindings in child envs
+   must NOT leak into _vm_globals (they'd overwrite real definitions). *)
 let () =
   Sx_types._env_bind_hook := Some (fun env name v ->
     if env == global_env then
@@ -476,6 +476,16 @@ let () =
     | [String src] -> List (Sx_parser.parse_all src)
     | _ -> raise (Eval_error "sx-parse: expected string"));
 
+  (* parse: same as server — unwraps single results, returns list for multiple.
+     Used by boot.sx (page scripts, suspense) and engine.sx (marsh update). *)
+  bind "parse" (fun args ->
+    match args with
+    | [String src] | [SxExpr src] ->
+      let exprs = Sx_parser.parse_all src in
+      (match exprs with [e] -> e | _ -> List exprs)
+    | [v] -> v
+    | _ -> raise (Eval_error "parse: expected string"));
+
   bind "sx-serialize" (fun args ->
     match args with
     | [v] -> String (inspect v)