Delete evaluator.py shim: all imports go directly to bootstrapped sx_ref.py

EvalError moved to types.py. All 27 files updated to import eval_expr,
trampoline, call_lambda, etc. directly from shared.sx.ref.sx_ref instead
of through the evaluator.py indirection layer. 320/320 spec tests pass.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/sx/ref/run_js_sx.py

@@ -49,7 +49,7 @@ def load_js_sx() -> dict:
 
     exprs = parse_all(source)
 
-    from shared.sx.evaluator import evaluate, make_env
+    from shared.sx.ref.sx_ref import evaluate, make_env
 
     env = make_env()
     for expr in exprs:
@@ -74,7 +74,7 @@ def compile_ref_to_js(
         spec_modules: List of spec modules (deps, router, signals). None = auto.
     """
     from datetime import datetime, timezone
-    from shared.sx.evaluator import evaluate
+    from shared.sx.ref.sx_ref import evaluate
 
     ref_dir = _HERE
     env = load_js_sx()