feature: support _rowoffset in scan filters beyond the IN-list take lowering

_rowoffset can be used in a scan filter only when the predicate lowers into TakeOperation::RowOffsets, that is a positive IN list of literal offsets. Anything else is rejected. On main at ebba5814c:

ds.scan().filter("_rowoffset > 2")

fails with Column _rowoffset does not exist from Projection::union_column, which has arms for _rowid, _rowaddr, _row_last_updated_at_version and _row_created_at_version but none for _rowoffset (rust/lance-core/src/datatypes/schema.rs:1272). Adding that arm is not sufficient on its own: the filtered read then rejects the predicate at rust/lance-datafusion/src/planner.rs:1089 with FieldNotFound { field: _rowoffset, valid_fields: [idx, _rowid, _rowaddr] }, because the column is never materialized into the schema the filter is planned against.

_rowoffset is a pure function of _rowaddr (the low 32 bits), so the shape of the fix is to request _rowaddr whenever a filter mentions _rowoffset and compute the derived column before filter refinement. That makes every predicate over it work, not just the IN shape.

This came up while fixing #9080: a negated _rowoffset list used to lower into a take of the listed offsets, which returned the complement of what was asked. That is now rejected instead, so the wrong-results bug is gone, but the predicate still cannot be answered.

Start with Projection::union_column in rust/lance-core/src/datatypes/schema.rs:1272 and the filtered-read planning path at rust/lance-datafusion/src/planner.rs:1089. Trace how scan filters request and materialize columns, then verify that predicates using _rowoffset beyond positive literal IN lists are accepted and produce the expected filtered rows.