Binary StartsWith visitors compare bytes as strings

[kevinjqliu]

Several StartsWith / NotStartsWith visitors appear to compare binary values by converting them with str(...), which gives incorrect byte-prefix behavior.

Examples:

StartsWith("x", b"a") on b"aa" -> False  # expected True
NotStartsWith("x", b"a") on b"aa" -> True # expected False

This also affects planning paths:

inclusive metrics for a file containing only b"aa":
StartsWith("x", b"a") -> False  # unsafe skip

Manifest evaluation for binary StartsWith can also raise TypeError when comparing decoded bytes bounds to a str prefix.

Relevant code: pyiceberg/expressions/visitors.py starts-with handling in expression, manifest, metrics, and residual visitors.

[kevinjqliu]

Verified against the current worktree.

StartsWith("x", b"a") on b"aa" -> False  # expected True
NotStartsWith("x", b"a") on b"aa" -> True # expected False

Planning impact also reproduces:

inclusive metrics for a file containing only b"aa":
StartsWith("x", b"a") -> False  # unsafe skip

Manifest evaluation for binary StartsWith raises TypeError comparing decoded bytes bounds to a str prefix.