List project environment variables

## Usage

`circleci envvar list [flags]`

Aliases: `circleci envvar ls`

## Flags

| Flag               | Description                                                                       |
| ------------------ | --------------------------------------------------------------------------------- |
| `--jq string`      | Process values from the response using jq syntax (see `circleci help formatting`) |
| `--json`           | Output as JSON                                                                    |
| `--project string` | Project slug (e.g. gh/org/repo); defaults to git remote                           |

Global flags: `-c, --config`, `--debug`, `--no-color`, `-q, --quiet` — see `circleci --help`.

## Examples

- List env vars for the current project: 
  `circleci envvar list`
- List env vars for a specific project: 
  `circleci envvar list --project gh/myorg/myrepo`
- Output as JSON: 
  `circleci envvar list --json`

## Details

List the environment variables defined for a CircleCI project.

Values are always masked in the response (shown as "xxxx") — CircleCI
does not expose secret values after they are set.

JSON fields: name, value

