feat!: expose native lance scan descriptor for comet - #624

## What

Adds `LanceArrowStreamScanner`, which plans a Lance fragment scan and
exports it as an Arrow C Data Interface stream (`ArrowArrayStream`) for
native consumers such as Apache Gluten / Velox.

## Why

This is the read-side building block for offloading Lance scans to a
native engine. Only the `ArrowArrayStream` C-struct address crosses the
JVM/native boundary, so the consumer's Arrow build and classloader do
not need to match lance-spark's — Gluten builds Arrow 15 to match Spark
3.5 / Velox, while the Lance Java SDK is on Arrow 18. Passing the raw
struct address sidesteps that mismatch entirely.

## How

- `LanceArrowStreamScanner.export(fragmentId, inputPartition)` returns a
`LanceArrowStream` handle exposing `stream()` / `streamAddress()`.
- All scan planning (column projection, filter pushdown, limit/offset,
row-id / row-address, batch size) is delegated to the existing
`LanceFragmentScanner`, so the exported stream yields exactly the same
rows in the same order as the Spark columnar reader.
- The Lance native core populates the caller-owned stream directly via
`LanceScanner#exportArrowStream(long)` (lance-format/lance#7259), so no
Arrow data is materialized on the JVM heap on this path.
- `LanceArrowStream` owns the exported stream and the scan behind it;
closing it releases the native scan (through the stream's release
callback) and then the scanner and dataset handles.

## Dependency

`exportArrowStream(long)` first ships in lance-core `11.0.0-beta.21`, so
this bumps `lance.version` from `11.0.0-beta.10` (isolated in its own
commit).

## Testing

- New `LanceArrowStreamScannerTest`: exports each fragment of the
bundled test table, re-imports it on the JVM (standing in for a native
consumer), and asserts the rows match the columnar reader — run under
the leak-checking allocator to verify the export/scanner lifecycle
releases cleanly.
- Existing `LanceFragmentColumnarBatchScannerTest` still passes
(regression on the touched `LanceFragmentScanner`).

## Related

- Complements #715 (Gluten write path).
- Distinct mechanism from #624 / #623 (serializable native scan
descriptor for datafusion-comet): this exposes a live Arrow C stream
handle rather than a re-plannable descriptor.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.8 <[email protected]>