Validate column names in Polars DataFrame.sort(), filter(), etc #5034

Describe the Bug

Pyrefly emits [unknown-column] when invalid column names are passed to select(), drop(), cast(). However, pyrefly does not do the same for schema-preserving operations like DataFrame.sort(), filter(), etc.

import polars as pl
df = pl.DataFrame({"date": [1]})
df.select("nonexistent")  # emits unknown-column, as expected.
df.sort("nonexistent")    # pyrefly is silent - unexpected!

Expectation: Pyrefly should validate column names even for schema-preserving operations.
Tested on pyrefly 1.3.1

Sandbox Link

No response

(Only applicable for extension issues) IDE Information

No response