fix(core): establish request context at every server-code entry point

Wraps the three additional entry points where user server code runs
outside fetchHandler's own context wrap:
- the server-function RPC path (/__wrnexus/rpc) intercepted before
  handlers.fetch in the dev server (index.ts) - what server.fn() travels
- the service RPC path (isRpcPath) inside fetchHandler, which runs
  implement()/implementStream() service code before ctx existed
- the HMR-sync handler, which runs real load blocks/actions via dispatch()

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

packages/dev-server/test/server-fn-rpc-request-context.test.ts

@@ -0,0 +1,27 @@
+import { expect, test } from "bun:test";
+import { getRequestContext } from "@wrnexus/core";
+import { withServerFnRequestContext } from "../src/index.ts";
+
+// The server-function RPC path ("/__wrnexus/rpc", what server.fn() calls from
+// the browser) is intercepted before fetchHandler in the dev server and would
+// otherwise run entirely outside the AsyncLocalStorage wrap. This is the
+// property that was broken: a handler invoked through that path must see the
+// request context, not `undefined`.
+test("a handler invoked through the server-function RPC path can read the request context", async () => {
+  let seen: unknown;
+  const innerHandler = async (request: Request): Promise<Response> => {
+    seen = getRequestContext();
+    return new Response("ok");
+  };
+
+  const wrapped = withServerFnRequestContext(innerHandler);
+  const request = new Request("http://localhost/__wrnexus/rpc", { method: "POST" });
+  await wrapped(request);
+
+  expect(seen).toBeDefined();
+  expect((seen as { req: Request }).req).toBe(request);
+});
+
+test("there is no context outside the wrap", () => {
+  expect(getRequestContext()).toBeUndefined();
+});