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>

examples/basic-app/app/pages/island-demo.wrn

@@ -0,0 +1,21 @@
+import Counter from "../islands/Counter"
+
+// React island demo. Route: /island-demo
+//
+// Counter.tsx is a plain React component: the compiler emits an island
+// placeholder here instead of a server-rendered component mount, and the
+// browser mounts it with createRoot.
+page IslandDemo {
+  seo {
+    title = "Island demo"
+    description = "Mounts a React island inside a server-rendered WRNexus page."
+    canonical = "/island-demo"
+  }
+
+  view {
+    <main>
+      <h1>React island</h1>
+      <Counter start={3} client:visible />
+    </main>
+  }
+}

examples/basic-app/app/routes.gen.ts

@@ -9,6 +9,7 @@ export interface Routes {
   "/client-only": Record<string, never>;
   "/dashboard": Record<string, never>;
   "/hello": Record<string, never>;
+  "/island-demo": Record<string, never>;
   "/language-tools": Record<string, never>;
   "/layout": Record<string, never>;
   "/login": Record<string, never>;
@@ -31,6 +32,7 @@ export interface RouteNames {
   "client.only": "/client-only";
   "dashboard": "/dashboard";
   "hello": "/hello";
+  "island.demo": "/island-demo";
   "language.tools": "/language-tools";
   "layout": "/layout";
   "login": "/login";
@@ -122,6 +124,7 @@ export function route<N extends RouteName>(
   "client.only": "/client-only",
   "dashboard": "/dashboard",
   "hello": "/hello",
+  "island.demo": "/island-demo",
   "language.tools": "/language-tools",
   "layout": "/layout",
   "login": "/login",

examples/basic-app/app/types/wrnexus.generated.d.ts

@@ -13,7 +13,7 @@ declare namespace WRNexusGenerated {
       : never;
   type RealtimeMessage<T> = T extends import("@wrnexus/core").RoomDefinition<any, infer M> ? M : unknown;
   type QueuePayload<T> = T extends import("@wrnexus/queue").JobDefinition<infer I> ? I : unknown;
-  type RouteName = "about" | "async.data" | "chat" | "client.only" | "dashboard" | "hello" | "index" | "language.tools" | "layout" | "login" | "modal" | "navigation" | "partial.static" | "platform.showcase" | "reactive" | "server.actions" | "table" | "test" | "ui";
+  type RouteName = "about" | "async.data" | "chat" | "client.only" | "dashboard" | "hello" | "index" | "island.demo" | "language.tools" | "layout" | "login" | "modal" | "navigation" | "partial.static" | "platform.showcase" | "reactive" | "server.actions" | "table" | "test" | "ui";
   type ApiRoute = "/api/accounts" | "/api/echo" | "/api/graphql-example" | "/api/hello" | "/api/invite" | "/api/login" | "/api/logout" | "/api/me" | "/api/typed-user" | "/api/users/csr" | "/api/users/ssr" | "/api/webhooks/payment";
   type RealtimeRoute = "/realtime/chat" | "/realtime/hello";
   type EnvironmentKey = "APP_LABEL" | "DATABASE_URL" | "DEMO_SHARED" | "HOST" | "NODE_ENV" | "PORT" | "SESSION_SECRET" | "UAT_ONLY";