test(ModelPicker): add keyboard handling to mock Select component

Cause: The issue was that the mock `Select` component in the
test didn't implement keyboard handling. When the test sent keys via
`stdin.write()`, they weren't being processed because the mock was just
rendering static text without `useInput`.

Fix: Added `useInput` to the mock `Select` component to handle the Enter
key, which allows keyboard events to flow through the component
hierarchy properly.

Author: remarkablemark

src/components/ModelPicker.test.tsx

@@ -9,7 +9,7 @@ const { mockListModels, mockOnChange } = vi.hoisted(() => ({
 }));
 
 vi.mock('@inkjs/ui', async () => {
-  const { Text } = await import('ink');
+  const { Text, useInput } = await import('ink');
   return {
     Spinner: ({ label }: { label?: string }) => (
       <Text>{`⏳${label ?? ''}`}</Text>
@@ -23,6 +23,13 @@ vi.mock('@inkjs/ui', async () => {
       onChange?: (value: string) => void;
     }) => {
       mockOnChange.mockImplementation((v) => onChange?.(v));
+
+      useInput((_input, key) => {
+        if (key.return && options.length > 0) {
+          onChange?.(options[0].value);
+        }
+      });
+
       return (
         <>
           {options.map(({ value, label }) => (