feat: Make the axios migration work end to end

.agents/skills/data-client/SKILL.md

@@ -15,6 +15,9 @@ Read `../data-client-setup/SKILL.md` (next to this one) and follow it. It isn't
 installs; the user asking to add or use Data Client in this app is the go-ahead. If they only asked about Data
 Client, answer and offer to set it up instead.
 
+To only swap an HTTP client (axios, fetch, ky, superagent, got) for `@data-client/rest` endpoints, without a provider
+or store changes, follow `../data-client-setup/references/data-client-rest-setup.md` instead.
+
 ## Set up
 
 Load the skill for the work. If it isn't available by name but its package is installed, run
@@ -30,9 +33,10 @@ ship into the project's skill folder, then read `.claude/skills/<skill>/SKILL.md
 | Tests | `data-client-react-testing` or `data-client-vue-testing` | `react` or `vue` |
 | WebSockets, SSE, polling, global side effects | `data-client-manager` | `core` |
 
-To add a protocol the app doesn't depend on yet, or to write GraphQL queries or wrap async functions, follow its guide
-in `data-client-setup` (`../data-client-setup/references/`): `data-client-rest-setup.md`,
-`data-client-graphql-setup.md` or `data-client-endpoint-setup.md`, installing only packages the app lacks. They
+To add a protocol the app doesn't depend on yet, move axios or fetch calls to REST endpoints, write GraphQL queries or
+wrap async functions, follow its guide in `data-client-setup` (`../data-client-setup/references/`):
+`data-client-rest-setup.md`, `data-client-graphql-setup.md` or `data-client-endpoint-setup.md`, installing only packages
+the app lacks. They
 aren't loaded by name.
 
-If a skill named here isn't installed, follow [references/install.md](references/install.md).
+If a skill named here isn't installed, follow [Installing a missing skill](references/install.md).

.changeset/axios-codemod-calls.md

@@ -0,0 +1,31 @@
+---
+'@data-client/codemods': patch
+---
+
+`axios-to-rest` now turns axios calls into working endpoint calls
+
+It used to swap `api.get(url)` for `new ApiEndpoint({ path })` without calling it, so `await` returned the endpoint
+instead of data, and POST bodies and `params` were dropped. Now it calls the endpoint, passes path params, `params`,
+query strings and bodies as arguments, and reads the body where the code read `.data`:
+
+```ts
+// before the codemod
+const res = await api.get<Post>(`/posts/${id}`, { params: { expand: 'author' } });
+return res.data;
+```
+
+```ts
+// after the codemod
+const res = await (new ApiEndpoint({
+  path: '/posts/:id',
+  searchParams: {} as Record<string, unknown>,
+})({ id, expand: 'author' }) as Promise<Post>);
+return res;
+```
+
+Calls through an `axios.create()` instance that another file exports, like `import { api } from './client'`, are
+converted too, and their import becomes the instance's new endpoint class.
+
+Anything it can't convert, such as interceptors, `timeout` or `isAxiosError()`, gets a `// TODO(data-client):` comment
+that links the [axios migration guide](https://dataclient.io/rest/guides/axios-migration) section covering it. Search
+for `TODO(data-client)` after running it.