refactor: rename Batch to Partition and update related types and channels for consistency

internal/app/models/main.go

@@ -4,14 +4,14 @@ import "github.com/google/uuid"
 
 type UnknownRowValues = []any
 
-type Chunk struct {
+type Batch struct {
 	Id           uuid.UUID
-	BatchId      uuid.UUID
+	PartitionId  uuid.UUID
 	Data         []UnknownRowValues
 	RetryCounter int
 }
 
-type Batch struct {
+type Partition struct {
 	Id                    uuid.UUID
 	ParentId              uuid.UUID
 	LowerLimit            int64