A panic in a JSON route's handler answered 500 with an empty body,
because the router's recoverer sits outside the middleware that adds
`@meta`. `JSONValidationMiddleware` now wraps the handler in the same
recoverer, and answers the panic with the JSON error body.
`/status.json` and the health check answered chi's empty 405 to any
method they do not take. They now answer with the same JSON 405 as the
routes under `/api/v1` and `/ip`.
The home page's IP lookup card showed only the answer's `data`. It now
shows the whole answer, `@meta` included.
A table test checks `@meta` on every JSON route, in its successes and
its errors.
Model: opus-5-5
sneak