refactor: extract partition iteration and unify group selection

Move partition iteration logic to obikdump, introducing a FilteredPartitionIter trait over IndexCache for batch-oriented scanning with configurable data retrieval and early termination. Consolidate ingroup and outgroup index storage in GroupQuorumFilter into a unified Selection struct driven by predicate matching. Update dependency manifests to include obikidxcache, rayon, and obikentropy, and remove the deprecated dump_layer module while adjusting public API re-exports.

src/Cargo.lock

@@ -1524,7 +1524,10 @@ name = "obikdump"
 version = "0.1.0"
 dependencies = [
  "obikfilter",
+ "obikidxcache",
  "obikindex",
+ "obikseq",
+ "rayon",
 ]
 
 [[package]]
@@ -1539,6 +1542,7 @@ name = "obikfilter"
 version = "0.1.0"
 dependencies = [
  "obicompactvec",
+ "obikentropy",
  "obikindex",
  "obikseq",
  "obiskio",