Remove invoke from platform interfaces, add cek-call integration tests

- platform_js.py: remove invoke function definition and PRIMITIVES
  registration, switch domListen handler wrapping to cek-call
- platform_py.py: remove invoke function definition
- run_signal_tests.py: remove invoke patch, use cek_call in batch wrapper
- run_cek_reactive_tests.py: remove invoke, fix primitive lookup to use
  two-level is_primitive/get_primitive, increase recursion limit for
  interpreted CEK evaluation
- test-cek-reactive.sx: add 7 new tests covering cek-call dispatch with
  computed, effect, cleanup, batch coalescing

All 79 tests pass (20 signal + 43 CEK + 16 CEK reactive).

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

shared/sx/ref/run_signal_tests.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 """Run test-signals.sx using the bootstrapped evaluator with signal primitives.
 
-Uses bootstrapped signal functions from sx_ref.py directly, patching invoke
+Uses bootstrapped signal functions from sx_ref.py directly, patching apply
 to handle SX lambdas from the interpreter (test expressions create lambdas
 that need evaluator dispatch).
 """
@@ -25,14 +25,9 @@ sx_ref.trampoline = trampoline
 # Build env with primitives
 env = make_env()
 
-# --- Patch invoke and apply BEFORE anything else ---
-# Test expressions create SX Lambdas that bootstrapped code calls via invoke/apply.
-# Patch the module-level functions so all bootstrapped functions see them.
-def _invoke(f, *args):
-    if isinstance(f, Lambda):
-        return trampoline(eval_expr([f] + list(args), env))
-    return f(*args)
-sx_ref.__dict__["invoke"] = _invoke
+# --- Patch apply BEFORE anything else ---
+# Test expressions create SX Lambdas that bootstrapped code calls via apply.
+# Patch the module-level function so all bootstrapped functions see it.
 
 # apply is used by swap! and other forms to call functions with arg lists
 def _apply(f, args):
@@ -124,7 +119,7 @@ env["effect"] = sx_ref.effect
 # Wrap it to work correctly in the test context.
 def _batch(thunk):
     sx_ref._batch_depth = getattr(sx_ref, '_batch_depth', 0) + 1
-    _invoke(thunk)
+    sx_ref.cek_call(thunk, None)
     sx_ref._batch_depth -= 1
     if sx_ref._batch_depth == 0:
         queue = list(sx_ref._batch_queue)
@@ -145,7 +140,6 @@ env["flush-subscribers"] = sx_ref.flush_subscribers
 env["dispose-computed"] = sx_ref.dispose_computed
 env["with-island-scope"] = sx_ref.with_island_scope
 env["register-in-scope"] = sx_ref.register_in_scope
-env["invoke"] = _invoke
 env["callable?"] = sx_ref.is_callable
 
 # Load test framework