feat(core-*): add Vitest configs + composition tests

core-api: appRouter exposes all 4 feature routers + blog procedure shape.
core-cms: payloadConfig registers all collections + globals.
core-trpc: client + provider exports verified.

Spec: §6.1, §6.6

packages/core-api/src/router.test.ts

@@ -0,0 +1,19 @@
+import { describe, it, expect } from "vitest";
+import { appRouter } from "./root";
+
+describe("appRouter composition", () => {
+  it("exposes auth, blog, marketingPages, navigation routers", () => {
+    const procedures = appRouter._def.procedures;
+    const keys = Object.keys(procedures);
+    expect(keys.some((k) => k.startsWith("auth."))).toBe(true);
+    expect(keys.some((k) => k.startsWith("blog."))).toBe(true);
+    expect(keys.some((k) => k.startsWith("marketingPages."))).toBe(true);
+    expect(keys.some((k) => k.startsWith("navigation."))).toBe(true);
+  });
+
+  it("blog router has expected procedures", () => {
+    const procedures = appRouter._def.procedures;
+    expect(procedures).toHaveProperty("blog.articleBySlug");
+    expect(procedures).toHaveProperty("blog.listArticles");
+  });
+});