docs: added AI usage into the README

README.md

@@ -54,3 +54,24 @@ Before a pull request can be merged:
 3. **Pushing new commits dismisses the approval**, so if you change something
    after being approved, ask for another review. This is deliberate: what was
    approved is what gets merged.
+
+## Use of AI in this project
+
+We have used Claude (through Claude Code) as a tool during development. In
+short, it was used for:
+
+- **Code review and requirements checks.** Reviewing our own code before
+  pull requests, and checking the project against the functional and
+  technical requirements.
+- **Test setup.** Setting up Vitest and React Testing Library and writing the
+  initial tests. We then removed the tests that did not add value and wrote
+  new ones ourselves (for example the tests for `fetchWork`, `toDescription`
+  and `SearchBar`).
+- **Understanding.** Explaining how mocking, spies and `vi.mock` work, so that
+  we can explain every test in the project ourselves.
+- **Open Library API.** Working out the shape of some API responses, such as
+  the `description` field of a work.
+
+Where AI contributed directly to a piece of code, there is a comment saying
+so, for example in [src/api/types.ts](src/api/types.ts) and
+[src/main.tsx](src/main.tsx).