SX renderer: adapter-html.sx as sole renderer, conditions, pattern matching

Evaluator: conditions/restarts, pattern matching, render-trace support.
adapter-html.sx: full SX-defined HTML renderer replacing native OCaml.
spec/render.sx: updated render mode helpers.
sx_browser.ml: use SX render-to-html instead of native.
sx_ref.ml: evaluator updates for conditions + match.
Bootstrap + transpiler updates for new forms.

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

hosts/ocaml/bin/sx_http.ml

@@ -226,7 +226,7 @@ let sx_render_to_html expr env =
     let result = Sx_ref.cek_call fn (List [expr; Env env]) in
     match result with String s -> s | _ -> Sx_runtime.value_to_str result
   else
-    Sx_render.render_to_html expr env
+    Sx_render.sx_render_to_html env expr env
 
 
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