Remove cssx.sx references from WASM test scripts

cssx.sx was deleted in the CSSX → ~tw migration. The test scripts
(test_wasm.sh, test_wasm_native.js, bisect_sxbc.sh) still referenced
it, causing ENOENT during WASM build step 5.

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

hosts/ocaml/browser/bisect_sxbc.sh

@@ -14,7 +14,7 @@ FILES=(
   render core-signals signals deps router page-helpers freeze
   bytecode compiler vm dom browser
   adapter-html adapter-sx adapter-dom
-  cssx boot-helpers hypersx
+  boot-helpers hypersx
   harness harness-reactive harness-web
   engine orchestration boot
 )