Support delete-file-backed row changes in incremental changelog scans

[fallintoplace]

Background

Incremental changelog scanning was added in #1883 to mirror Java's newIncrementalChangelogScan() API.

The first implementation handles file-level changes from data manifests. This issue tracks delete-file-backed row changes and keeps the related work together.

Current status: file-level changelog planning is implemented in #1883. Snapshots with delete manifests are still rejected.

Implemented

• Table.NewIncrementalChangelogScan
• INSERT tasks for added data files
• DELETE tasks for removed data files
• Snapshot boundaries, change ordinals, and commit snapshot IDs
• Filters, residuals, row-lineage task fields, and local planning

Planned

• Define changelog task and reader types for added rows, deleted data files, and deleted rows
• Plan position and equality delete files across snapshot ranges
• Preserve added versus existing delete-file semantics
• Support deletion vectors and v3 row lineage
• Add end-to-end tests for same-snapshot changes, prior deletes, file removal, schema evolution, filters, and boundaries
• Add documentation and decide remote planning support

Implementation notes

• The normal scan path removes deleted rows while reading. A changelog scan needs to emit rows removed by the current snapshot.
• A deleted data file must be read with delete files that existed before the file was removed.
• A row-level delete needs to distinguish delete files added by the current snapshot from delete files that were already present.
• The task shape should follow Java's AddedRowsScanTask, DeletedDataFileScanTask, and DeletedRowsScanTask, with Go naming.
• Position-delete, equality-delete, and deletion-vector readers already exist in the table scan and inspection paths. This work should reuse them where possible.
• Remote planning can remain unsupported initially.

Related work

• PR #1883
• Table.Inspect metadata table support #1703 (related groundwork only)
• Delete-file metadata support #1699
• Position deletes metadata support #1747

References

• Java changelog planner
• Java changelog task types
• Iceberg table specification

[dgvj-work]

I'd like to pick this up if nobody else is on it — extending incremental changelog scans to cover delete-file-backed row changes, on top of the file-level work in #1883.

I'll start with the planned task/reader types and a PR when I have something reviewable.

[fallintoplace]

@dgvj-work Sure, this is an important feature.