Fix quasiquote flattening bug, decouple relations from evaluator

- Fix qq-expand in eval.sx: use concat+list instead of append to prevent
  nested lists from being flattened during quasiquote expansion
- Update append primitive to match spec ("if x is list, concatenate")
- Rebuild sx_ref.py with quasiquote fix
- Make relations.py self-contained: parse defrelation AST directly
  without depending on the evaluator (25/25 tests pass)
- Replace hand-written JSEmitter with js.sx self-hosting bootstrapper
- Guard server-only tests in test-eval.sx with runtime check

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

sx/sxc/pages/helpers.py

@@ -384,57 +384,47 @@ def _self_hosting_data(ref_dir: str) -> dict:
 
 
 def _js_self_hosting_data(ref_dir: str) -> dict:
-    """Run js.sx live: load into evaluator, translate spec files, diff against G0."""
+    """Run js.sx live: load into evaluator, translate all spec defines."""
     import os
-    from shared.sx.parser import parse_all
     from shared.sx.types import Symbol
-    from shared.sx.evaluator import evaluate, make_env
-    from shared.sx.ref.bootstrap_js import extract_defines, JSEmitter
+    from shared.sx.evaluator import evaluate
+    from shared.sx.ref.run_js_sx import load_js_sx
+    from shared.sx.ref.platform_js import extract_defines
 
     try:
         js_sx_path = os.path.join(ref_dir, "js.sx")
         with open(js_sx_path, encoding="utf-8") as f:
             js_sx_source = f.read()
 
-        exprs = parse_all(js_sx_source)
-        env = make_env()
-        for expr in exprs:
-            evaluate(expr, env)
-
-        emitter = JSEmitter()
+        env = load_js_sx()
 
         # All spec files
         all_files = sorted(
             f for f in os.listdir(ref_dir) if f.endswith(".sx")
         )
         total = 0
-        matched = 0
         for filename in all_files:
             filepath = os.path.join(ref_dir, filename)
             with open(filepath, encoding="utf-8") as f:
                 src = f.read()
             defines = extract_defines(src)
             for name, expr in defines:
-                g0_stmt = emitter.emit_statement(expr)
                 env["_def_expr"] = expr
-                g1_stmt = evaluate(
+                evaluate(
                     [Symbol("js-statement"), Symbol("_def_expr")], env
                 )
                 total += 1
-                if g0_stmt.strip() == g1_stmt.strip():
-                    matched += 1
 
-        status = "identical" if matched == total else "mismatch"
+        status = "ok"
 
     except Exception as e:
         js_sx_source = f";; error loading js.sx: {e}"
-        matched, total = 0, 0
+        total = 0
         status = "error"
 
     return {
         "bootstrapper-not-found": None,
         "js-sx-source": js_sx_source,
-        "defines-matched": str(matched),
         "defines-total": str(total),
         "js-sx-lines": str(len(js_sx_source.splitlines())),
         "verification-status": status,