SxExpr aser wire format fix + Playwright test infrastructure + blob protocol

Aser serialization: aser-call/fragment now return SxExpr instead of String.
serialize/inspect passes SxExpr through unquoted, preventing the double-
escaping (\" → \\\" ) that broke client-side parsing when aser wire format
was output via raw! into <script> tags. Added make-sx-expr + sx-expr-source
primitives to OCaml and JS hosts.

Binary blob protocol: eval, aser, aser-slot, and sx-page-full now send SX
source as length-prefixed blobs instead of escaped strings. Eliminates pipe
desync from concurrent requests and removes all string-escape round-trips
between Python and OCaml.

Bridge safety: re-entrancy guard (_in_io_handler) raises immediately if an
IO handler tries to call the bridge, preventing silent deadlocks.

Fetch error logging: orchestration.sx error callback now logs method + URL
via log-warn. Platform catches (fetchAndRestore, fetchPreload, bindBoostForm)
also log errors instead of silently swallowing them.

Transpiler fixes: makeEnv, scopePeek, scopeEmit, makeSxExpr added as
platform function definitions + transpiler mappings — were referenced in
transpiled code but never defined as JS functions.

Playwright test infrastructure:
- nav() captures JS errors and fails fast with the actual error message
- Checks for [object Object] rendering artifacts
- New tests: delete-row interaction, full page refresh, back button,
  direct load with fresh context, code block content verification
- Default base URL changed to localhost:8013 (standalone dev server)
- docker-compose.dev-sx.yml: port 8013 exposed for local testing
- test-sx-build.sh: build + unit tests + Playwright smoke tests

Geography content: index page component written (sx/sx/geography/index.sx)
describing OCaml evaluator, wire formats, rendering pipeline, and topic
links. Wiring blocked by aser-expand-component children passing issue.

Tests: 1080/1080 JS, 952/952 OCaml, 66/66 Playwright

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

shared/sx/query_executor.py

@@ -21,10 +21,6 @@ async def execute_query(query_def: QueryDef, params: dict[str, str]) -> Any:
     """
     from .jinja_bridge import get_component_env, _get_request_context
     import os
-    if os.environ.get("SX_USE_REF") == "1":
-        from .ref.async_eval_ref import async_eval
-    else:
-        from .async_eval import async_eval
 
     env = dict(get_component_env())
     env.update(query_def.closure)
@@ -38,6 +34,26 @@ async def execute_query(query_def: QueryDef, params: dict[str, str]) -> Any:
             val = int(val)
         env[param] = val
 
+    if os.environ.get("SX_USE_OCAML") == "1":
+        from .ocaml_bridge import get_bridge
+        from .parser import serialize, parse_all
+        from .pages import _wrap_with_env
+        bridge = await get_bridge()
+        sx_text = _wrap_with_env(query_def.body, env)
+        ctx = {"_helper_service": ""}
+        raw = await bridge.eval(sx_text, ctx=ctx)
+        if raw:
+            parsed = parse_all(raw)
+            result = parsed[0] if parsed else None
+        else:
+            result = None
+        return _normalize(result)
+
+    if os.environ.get("SX_USE_REF") == "1":
+        from .ref.async_eval_ref import async_eval
+    else:
+        from .async_eval import async_eval
+
     ctx = _get_request_context()
     result = await async_eval(query_def.body, env, ctx)
     return _normalize(result)
@@ -50,10 +66,6 @@ async def execute_action(action_def: ActionDef, payload: dict[str, Any]) -> Any:
     """
     from .jinja_bridge import get_component_env, _get_request_context
     import os
-    if os.environ.get("SX_USE_REF") == "1":
-        from .ref.async_eval_ref import async_eval
-    else:
-        from .async_eval import async_eval
 
     env = dict(get_component_env())
     env.update(action_def.closure)
@@ -64,6 +76,26 @@ async def execute_action(action_def: ActionDef, payload: dict[str, Any]) -> Any:
         val = payload.get(param, payload.get(snake, NIL))
         env[param] = val
 
+    if os.environ.get("SX_USE_OCAML") == "1":
+        from .ocaml_bridge import get_bridge
+        from .parser import serialize, parse_all
+        from .pages import _wrap_with_env
+        bridge = await get_bridge()
+        sx_text = _wrap_with_env(action_def.body, env)
+        ctx = {"_helper_service": ""}
+        raw = await bridge.eval(sx_text, ctx=ctx)
+        if raw:
+            parsed = parse_all(raw)
+            result = parsed[0] if parsed else None
+        else:
+            result = None
+        return _normalize(result)
+
+    if os.environ.get("SX_USE_REF") == "1":
+        from .ref.async_eval_ref import async_eval
+    else:
+        from .async_eval import async_eval
+
     ctx = _get_request_context()
     result = await async_eval(action_def.body, env, ctx)
     return _normalize(result)