## Summary
Given a statement like `colors = 6`, we currently treat the cell as an
automagic (since `colors` is an automagic) -- i.e., we assume it's
equivalent to `%colors = 6`. This PR adds some additional detection
whereby if the statement is an _assignment_, we avoid treating it as
such. I audited the list of automagics, and I believe this is safe for
all of them.
Closes https://github.com/astral-sh/ruff/issues/8526.
Closes https://github.com/astral-sh/ruff/issues/9648.
## Test Plan
`cargo test`
