Panic if the `path` matcher receives as input a URL with a host

I have bumped into users trying the following:

```rust
Mock::given(path("https://domain.com/abcd"));
```

with an expectation that it will match incoming requests for `/abcd`.
In reality, they should write:

```rust
Mock::given(path("/abcd"));
```

to achieve the desired outcome.

`path` should panic if the input contains a host, with an helpful suggestion pointing at the right usage pattern.

Start by locating the `path` matcher entry point and its existing tests. Reproduce the URL-with-host input, then verify that it panics with guidance toward the path-only form while inputs such as `/abcd` retain their current matching behavior.

Written by the indexing model from the issue text.