Restore hyperscript work on stable site base (908f4f80)

Reset to last known-good state (908f4f80) where links, stepper, and
islands all work, then recovered all hyperscript implementation,
conformance tests, behavioral tests, Playwright specs, site sandbox,
IO-aware server loading, and upstream test suite from f271c88a.

Excludes runtime changes (VM resolve hook, VmSuspended browser handler,
sx_ref.ml guard recovery) that need careful re-integration.

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

hosts/ocaml/browser/compile-modules.js

@@ -80,7 +80,11 @@ const FILES = [
   'dom.sx', 'browser.sx', 'adapter-html.sx', 'adapter-sx.sx', 'adapter-dom.sx',
   'tw-layout.sx', 'tw-type.sx', 'tw.sx',
   'boot-helpers.sx', 'hypersx.sx', 'harness.sx', 'harness-reactive.sx',
-  'harness-web.sx', 'engine.sx', 'orchestration.sx', 'boot.sx',
+  'harness-web.sx', 'engine.sx', 'orchestration.sx',
+  // Hyperscript modules — loaded on demand via transparent lazy loader
+  'hs-tokenizer.sx', 'hs-parser.sx', 'hs-compiler.sx', 'hs-runtime.sx',
+  'hs-integration.sx',
+  'boot.sx',
 ];
 
 
@@ -339,6 +343,18 @@ function libKey(spec) {
   return spec.replace(/^\(/, '').replace(/\)$/, '');
 }
 
+// Extract top-level (define name ...) symbols from a non-library file
+function extractDefines(source) {
+  const names = [];
+  const re = /^\(define\s+(\S+)/gm;
+  let m;
+  while ((m = re.exec(source)) !== null) {
+    const name = m[1];
+    if (name && !name.startsWith('(') && !name.startsWith(':')) names.push(name);
+  }
+  return names;
+}
+
 const manifest = {};
 let entryFile = null;
 
@@ -360,6 +376,18 @@ for (const file of FILES) {
   } else if (deps.length > 0) {
     // Entry point (no define-library, has imports)
     entryFile = { file: sxbcFile, deps: deps.map(libKey) };
+  } else {
+    // Non-library file (e.g. hyperscript modules) — extract top-level defines
+    // as exports so the transparent lazy loader can resolve symbols to files.
+    const defines = extractDefines(src);
+    if (defines.length > 0) {
+      const key = file.replace(/\.sx$/, '');
+      manifest[key] = {
+        file: sxbcFile,
+        deps: [],
+        exports: defines,
+      };
+    }
   }
 }