Wire SX_USE_REF=1 switching through all route intermediaries

jinja_bridge, helpers, handlers, query_executor now conditionally
import from ref/sx_ref and ref/async_eval_ref when SX_USE_REF=1.

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

shared/sx/jinja_bridge.py

@@ -27,7 +27,11 @@ from typing import Any
 
 from .types import NIL, Component, Keyword, Macro, Symbol
 from .parser import parse
-from .html import render as html_render, _render_component
+import os as _os
+if _os.environ.get("SX_USE_REF") == "1":
+    from .ref.sx_ref import render as html_render, render_html_component as _render_component
+else:
+    from .html import render as html_render, _render_component
 
 
 # ---------------------------------------------------------------------------
@@ -169,7 +173,10 @@ def register_components(sx_source: str) -> None:
                   (div :class "..." (div :class "..." title)))))
         ''')
     """
-    from .evaluator import _eval as _raw_eval, _trampoline
+    if _os.environ.get("SX_USE_REF") == "1":
+        from .ref.sx_ref import eval_expr as _raw_eval, trampoline as _trampoline
+    else:
+        from .evaluator import _eval as _raw_eval, _trampoline
     _eval = lambda expr, env: _trampoline(_raw_eval(expr, env))
     from .parser import parse_all
     from .css_registry import scan_classes_from_sx