fix(docs): correct mock documentation examples (#25384)

## Summary

- Fix `mock.mock.args` to `mock.mock.calls` in mock-functions.mdx (the
`.args` property doesn't exist)
- Fix mock.restore example to use module methods instead of spy
functions (calling spy functions after restore returns `undefined`)
- Add missing `vi` import in Vitest compatibility example

## Test plan

- [x] Verified each code block works by running tests against the debug
build

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Co-authored-by: Claude Bot <claude-bot@bun.sh>
Co-authored-by: Claude <noreply@anthropic.com>

docs/guides/test/mock-functions.mdx

@@ -60,7 +60,7 @@ test("random", async () => {
 
   expect(random).toHaveBeenCalled();
   expect(random).toHaveBeenCalledTimes(3);
-  expect(random.mock.args).toEqual([[1], [2], [3]]);
+  expect(random.mock.calls).toEqual([[1], [2], [3]]);
   expect(random.mock.results[0]).toEqual({ type: "return", value: a });
 });
 ```