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/tests/test_io_proxy.py

@@ -20,7 +20,7 @@ from shared.sx.deps import (
 
 def make_env(*sx_sources: str) -> dict:
     """Parse and evaluate component definitions into an env dict."""
-    from shared.sx.evaluator import _eval, _trampoline
+    from shared.sx.ref.sx_ref import eval_expr as _eval, trampoline as _trampoline
     env: dict = {}
     for source in sx_sources:
         exprs = parse_all(source)
@@ -282,7 +282,7 @@ class TestIoRoutingLogic:
     """
 
     def _eval(self, src, env):
-        from shared.sx.evaluator import _eval, _trampoline
+        from shared.sx.ref.sx_ref import eval_expr as _eval, trampoline as _trampoline
         result = None
         for expr in parse_all(src):
             result = _trampoline(_eval(expr, env))