feat(rpc): transport, server, client, http, mounting, docs (Tasks 5-11)

Brings the uncommitted body of work under version control so it cannot be
lost. Gates are green: 152 tests pass across rpc/router/dev-server,
typecheck, lint, format and check:public-api all clean.

NOT YET REVIEWED. None of Tasks 5-11 has had an independent task review, and
Task 4's second fix round was never re-reviewed either.

Known gaps against the plan, recorded here rather than discovered later:
- packages/rpc/test/{transport,server,client}.test.ts are ABSENT. The plan
  required a test file for each. server.ts holds the fail-closed identity and
  permission checks and currently has no direct coverage at all.
- rpc-endpoint.test.ts has 3 tests where the plan specified 9. Missing:
  unknown service, non-POST, malformed body, non-rpc passthrough, and the
  isInternalCaller sweep. This is the task where a reachable
  /__wrnexus/rpc/* makes every permission check in the workspace bypassable.
- http.test.ts has 3 of 7; integration.test.ts 2 of 3;
  services-discovery.test.ts 1 of 4.

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

packages/router/test/services-discovery.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, test } from "bun:test";
+import { mkdirSync, mkdtempSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { buildRouter } from "../src/index.ts";
+
+const root = join(import.meta.dir, ".tmp-services");
+mkdirSync(root, { recursive: true });
+
+describe("service discovery", () => {
+  test("discovers source services and skips generated files", () => {
+    const base = mkdtempSync(join(root, "app-"));
+    const services = join(base, "app", "services");
+    mkdirSync(services, { recursive: true });
+    mkdirSync(join(base, "app", "pages"), { recursive: true });
+    writeFileSync(join(services, "billing.ts"), "export default {};");
+    writeFileSync(join(services, "types.gen.ts"), "export type T = string;");
+    expect(buildRouter(join(base, "app")).services.map((service) => service.name)).toEqual([
+      "billing",
+    ]);
+  });
+});