fix: clean up onboarding + channel selection types

src/commands/onboarding/__tests__/test-utils.ts

@@ -6,7 +6,9 @@ import type { WizardPrompter } from "../../../wizard/prompts.js";
 export const makeRuntime = (overrides: Partial<RuntimeEnv> = {}): RuntimeEnv => ({
   log: vi.fn(),
   error: vi.fn(),
-  exit: vi.fn(),
+  exit: vi.fn((code: number) => {
+    throw new Error(`exit:${code}`);
+  }) as RuntimeEnv["exit"],
   ...overrides,
 });