feat(islands): wire islands end to end

The island pieces existed but nothing connected .wrn compilation to island
emission. Now:

- codegen emits a data-wrn-island placeholder for component tags bound to
  .tsx imports, keeping .wrn components on the normal mount path
- the dev pipeline and static build resolve island imports, thread the
  names into codegen, and build the bundles
- collectScripts adds /__wrnexus/islands.js only when island markup is
  present, so island-free pages still ship nothing
- island routes classify as static-interactive via hasIslands

Three bugs found by driving a real page in the browser:

1. The mount runtime was never built anywhere, so the bootstrap 404'd and
   no island mounted.
2. Building the runtime separately from the islands gave each its own copy
   of React: "Cannot read properties of null (reading 'useState')". The
   runtime is now an entrypoint of the same build so React stays in one
   shared chunk. The existing single-React test only compared bundles
   within one build and could not see across build boundaries.
3. Island props arrived as attribute strings, so start={3} was "3" and
   incrementing produced "31" then "311". Props now follow JSX semantics:
   {…} parses as JSON, quoted values stay strings, and a runtime
   expression is a WRN-ISLAND-PROPS build error rather than a silent
   wrong value.

island-codegen.ts no longer imports @wrnexus/core. Compiler modules are
bundled into the Node-only VS Code extension, which contains no other
packages, so a runtime import of core broke the editor compiler; the two
helpers are implemented locally and the core dependency is dropped again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/build-editor-compiler.mjs

@@ -34,28 +34,13 @@ function loadTypeScript() {
 
 const ts = loadTypeScript();
 
-// React island modules are not used by the editor: island-bundle.ts calls
-// Bun.build and island-codegen.ts imports @wrnexus/core, neither of which
-// exists in this Node-only bundle. They are unreachable from the editor entry,
-// so excluding them keeps Bun-only code out of the extension entirely.
-const EDITOR_EXCLUDED = ["island-bundle.ts", "island-codegen.ts"];
-function isEditorExcluded(path) {
-  return EDITOR_EXCLUDED.some((name) => path.endsWith(name));
-}
-
 function walk(dir) {
   const files = [];
   for (const entry of readdirSync(dir)) {
     const path = join(dir, entry);
     const stat = statSync(path);
     if (stat.isDirectory()) files.push(...walk(path));
-    else if (
-      stat.isFile() &&
-      path.endsWith(".ts") &&
-      !path.endsWith(".test.ts") &&
-      !isEditorExcluded(path)
-    )
-      files.push(path);
+    else if (stat.isFile() && path.endsWith(".ts") && !path.endsWith(".test.ts")) files.push(path);
   }
   return files;
 }