use moclojer to mock api (tldr.chat endpoints)

https://github.com/moclojer/moclojer

tldr.chat has a request limit, developing with limits is practically "impossible"

```yaml
- endpoint:
method: GET
path: /url/:url
response:
status: 200
headers:
Content-Type: text/markdown
body: >
The text describes a conversation between an orbiter in space and Houston, where the orbiter reports a problem with its O2 tank. The person in Houston responds dismissively and ends the call. The text also includes a humorous title text and a note about the preferred viewing conditions for xkcd.com.
- endpoint:
method: POST
path: /summarize
response:
status: 303
headers:
Content-Type: application/json
body:
```

Start with the repository's tldr.chat request paths and the moclojer example linked in the issue. Configure mocks for GET /url/:url and POST /summarize, then verify local development can use the mock responses without depending on tldr.chat's request limit.

Written by the indexing model from the issue text.