comark/cast/invalid-header · Start a cast with an asciinema v2 or v3 header

An asciinema cast starts with a JSON header that gives its version, 2 or 3, and the terminal's size. Without one the text isn't a cast, often because it's a plain log pasted into the block, and nothing renders. Record the session with asciinema rec, or write the header by hand.

Incorrect

::cast
```
$ pnpm deploy
The pond is live
```
::

lint-comark example.mdexample.md:1:1 comark/cast/invalid-header::cast 1 isn't an asciinema cast: its first line must be a JSON header with "version": 2 or 3.Record it with asciinema rec.✖ 1 problem

Correct

::cast
```json
{"version": 2, "width": 40, "height": 3}
[0.1, "o", "$ pnpm deploy\r\n"]
[0.4, "o", "The pond is live\r\n"]
```
::

lint-comark example.md✔ No problems