Delete sx_ref.py — OCaml is the sole SX evaluator

Removes the 5993-line bootstrapped Python evaluator (sx_ref.py) and all
code that depended on it exclusively. Both bootstrappers (JS + OCaml)
now use a new synchronous OCaml bridge (ocaml_sync.py) to run the
transpiler. JS build produces identical output; OCaml bootstrap produces
byte-identical sx_ref.ml.

Key changes:
- New shared/sx/ocaml_sync.py: sync subprocess bridge to sx_server.exe
- hosts/javascript/bootstrap.py: serialize defines → temp file → OCaml eval
- hosts/ocaml/bootstrap.py: same pattern for OCaml transpiler
- shared/sx/{html,async_eval,resolver,jinja_bridge,handlers,pages,deps,helpers}:
  stub or remove sx_ref imports; runtime uses OCaml bridge (SX_USE_OCAML=1)
- sx/sxc/pages: parse defpage/defhandler from AST instead of Python eval
- hosts/ocaml/lib/sx_primitives.ml: append handles non-list 2nd arg per spec
- Deleted: sx_ref.py, async_eval_ref.py, 6 Python test runners, misc ref/ files

Test results: JS 1078/1078, OCaml 1114/1114.
sx_docs SSR has pre-existing rendering issues to investigate separately.

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

shared/sx/jinja_bridge.py

@@ -30,17 +30,7 @@ from typing import Any
 
 from .types import NIL, Component, Island, Keyword, Lambda, Macro, Symbol
 from .parser import parse
-import os as _os
-if _os.environ.get("SX_USE_OCAML") == "1":
-    # OCaml kernel bridge — render via persistent subprocess.
-    # html_render and _render_component are set up lazily since the bridge
-    # requires an async event loop.  The sync sx() function falls back to
-    # the ref renderer; async callers use ocaml_bridge directly.
-    from .ref.sx_ref import render as html_render, render_html_component as _render_component
-elif _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
+from .html import render as html_render, _render_component
 
 _logger = logging.getLogger("sx.bridge")
 
@@ -413,17 +403,28 @@ def register_components(sx_source: str, *, _defer_postprocess: bool = False) ->
     When *_defer_postprocess* is True, skip deps/io_refs/hash computation.
     Call ``finalize_components()`` once after all files are loaded.
     """
-    from .ref.sx_ref import eval_expr as _raw_eval, trampoline as _trampoline
-    _eval = lambda expr, env: _trampoline(_raw_eval(expr, env))
     from .parser import parse_all
     from .css_registry import scan_classes_from_sx
 
     # Snapshot existing component names before eval
     existing = set(_COMPONENT_ENV.keys())
 
+    # Evaluate definitions — OCaml kernel handles everything.
+    # Python-side component registry is populated minimally for CSS/deps.
     exprs = parse_all(sx_source)
     for expr in exprs:
-        _eval(expr, _COMPONENT_ENV)
+        if (isinstance(expr, list) and expr and isinstance(expr[0], Symbol)
+                and expr[0].name in ("defcomp", "defisland", "defmacro",
+                                      "define", "defstyle", "deftype",
+                                      "defeffect", "defrelation", "defhandler")):
+            name_sym = expr[1] if len(expr) > 1 else None
+            name = name_sym.name if hasattr(name_sym, 'name') else str(name_sym) if name_sym else None
+            if name and expr[0].name in ("defcomp", "defisland"):
+                _COMPONENT_ENV[name] = Component(
+                    name=name.lstrip("~"),
+                    params=[], has_children=False,
+                    body=expr[-1], closure={},
+                )
 
     # Pre-scan CSS classes for newly registered components.
     all_classes: set[str] | None = None