fix(16): add async/await to createTestDb in route and MCP tests

Route and MCP test files were calling createTestDb() without await,
causing db to be a Promise object instead of a Drizzle instance.
Also rewrote auth route tests for OIDC-based auth (merge picked old version).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/routes/items.test.ts

@@ -4,8 +4,8 @@ import { categoryRoutes } from "../../src/server/routes/categories.ts";
 import { itemRoutes } from "../../src/server/routes/items.ts";
 import { createTestDb } from "../helpers/db.ts";
 
-function createTestApp() {
-	const { db, userId } = createTestDb();
+async function createTestApp() {
+	const { db, userId } = await createTestDb();
 	const app = new Hono();
 
 	// Inject test DB and userId into context for all routes
@@ -23,8 +23,8 @@ function createTestApp() {
 describe("Item Routes", () => {
 	let app: Hono;
 
-	beforeEach(() => {
-		const testApp = createTestApp();
+	beforeEach(async () => {
+		const testApp = await createTestApp();
 		app = testApp.app;
 	});