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/parser.py

@@ -41,7 +41,7 @@ def _resolve_sx_reader_macro(name: str):
     """
     try:
         from .jinja_bridge import get_component_env
-        from .evaluator import _trampoline, _call_lambda
+        from .ref.sx_ref import trampoline as _trampoline, call_lambda as _call_lambda
         from .types import Lambda
     except ImportError:
         return None