feat(core): define mapping readers with ordered compaction support

[LuQQiu]

What this adds

This PR defines the common read contract for one fragment-rewrite mapping:

async fn remap_row_id(&self, row_id: u64) -> Result<Option<u64>>;

async fn remap_row_ids(
    &self,
    row_ids: &[u64],
) -> Result<Vec<Option<u64>>>;

A row ID is a physical row address containing a fragment ID and row offset. A mapped row ID identifies the rewritten destination row; None means the source row was deleted.

remap_row_id is the required primitive. The default batch implementation calls it for each input in order. Mapping implementations can override the batch method to coalesce IO or translate more efficiently.

The contract requires batch results to preserve input order and duplicates and return one result per input. Addresses outside the mapping's source fragments return InvalidInput; corrupt persisted mappings return CorruptFile; storage errors propagate unchanged.

Ordered compaction

OrderedCompactionMapping adapts the existing RowAddrRemap bitmap/rank implementation to this contract:

source physical row ID
        │
        ▼
existing RowAddrRemap
        │
        ├── destination physical row ID
        └── None when deleted

It reuses the existing compaction mapping and validated fragment layout without duplicating source or destination metadata. The legacy FRI reader and writer remain unchanged.

This interface represents one mapping only. FRI lineage traversal, coverage derivation, and planner integration remain responsibilities of the common FRI reader. Stable-partition mappings implement the same interface in #9064.

Validation

Tests cover default batch delegation and error propagation, deleted rows, duplicate and out-of-order inputs, empty batches, single/batch equivalence, invalid source fragments, and out-of-range source offsets.

Validated with workspace Clippy and cargo fmt --all.

[lance-gatekeeper]

✅ Gate recommendation: approve.

The mapping seam remains appropriately scoped: ordered compaction preserves the existing bitmap/rank behavior, while the async contract lets external row-map implementations override batch reads for efficient I/O. The tests cover deletion, ordering, duplicates, invalid addresses, and single/batch equivalence.

With #9136 now merged, the intended dependency order is satisfied.

[jackye1995]

looks good to me!