[FR]: Ignore linting via `.gitattributes`

### What is the current behavior?

Putting `rules-lint-ignored=true` in `.gitattributes` excludes files from formatting, but lint errors still show up in `aspect lint`.

### Describe the feature

It'd be nice if linting could also respect `.gitattributes`, either with the same annotation or a different one.

Alternatively, having a way to pass the `no-lint` tag to all subpackages, or to instruct gazelle to emit this tag in subpackages, would be nice.

The goal being achieved here is to exclude e.g. `//users` (or `//vibe`) from linting by default; it may not even be a well-formed goal, so I will also happily accept better goals as resolutions for this FR.

Start by tracing how `aspect lint` handles `.gitattributes` and how the `no-lint` tag and Gazelle-generated subpackages are currently handled. Compare the proposed annotation and tag-propagation approaches, then identify the relevant existing tests. Done means an agreed mechanism reliably excludes the intended packages from linting and is covered by tests.

Written by the indexing model from the issue text.