feat(apps): add unit tests for providers + bind-production + cms config

web-next: bindAllProduction calls all 4 feature binders exactly once;
Providers renders children. web-tanstack: equivalent providers + bind tests.
cms: payload.config exports a SanitizedConfig with all expected collections.

Spec: §6.7, §9

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/cms/src/payload.config.test.ts

@@ -0,0 +1,20 @@
+import { describe, it, expect } from "vitest";
+import config from "./payload.config";
+
+describe("CMS app payload.config", () => {
+  it("registers all feature collections", async () => {
+    const resolved = await config;
+    const slugs = resolved.collections?.map((c) => c.slug) ?? [];
+    expect(slugs).toEqual(
+      expect.arrayContaining(["users", "articles", "pages", "media"]),
+    );
+  });
+
+  it("registers all feature globals", async () => {
+    const resolved = await config;
+    const slugs = resolved.globals?.map((g) => g.slug) ?? [];
+    expect(slugs).toEqual(
+      expect.arrayContaining(["site-settings", "header"]),
+    );
+  });
+});