Feature request: attributes "[no-stderr]" and "[no-stdout]"

## Problem

The syntax for piping an error to `/dev/null` and throwing a custom error is somewhat ugly at the moment:

```just
my-recipe:
run-my-command \
2>/dev/null || { echo "❌ Command failed - blah blah"; exit 1; }
```

## Solution

It would be super helpful if Just provided two new attributes, `[no-stderr]` and `[no-stdout]`, which could be used like this:

```just
# The string in the ("") is what gets thrown when there is an exit status (code 1)
[no-stderr("❌ Command failed - blah blah")]
my-recipe:
run-my-command
```

```just
# The string in the ("") is what gets thrown when there is an exit status (code 1)
[no-stdout("✅ Command worked - blah blah")]
my-recipe:
run-my-command
```

> [!NOTE]
> This attribute wouldn't ignore error codes. It would simply ignore the `stderr` output and throw another error instead.

The issue names no files, tests, or entry points. Start by tracing how existing recipe attributes are handled; done means the proposed [no-stderr(...)] and [no-stdout(...)] forms support the documented output and failure behavior.

Written by the indexing model from the issue text.