refactor: rename Batch to Partition across pipeline

Rename internal types and channels from Batch to Partition for consistency with the data model.

internal/app/models/main.go

@@ -0,0 +1,22 @@
+package models
+
+import "github.com/google/uuid"
+
+type UnknownRowValues = []any
+
+type Batch struct {
+	Id           uuid.UUID
+	PartitionId  uuid.UUID
+	Data         []UnknownRowValues
+	RetryCounter int
+}
+
+type Partition struct {
+	Id                    uuid.UUID
+	ParentId              uuid.UUID
+	LowerLimit            int64
+	UpperLimit            int64
+	IsLowerLimitInclusive bool
+	ShouldUseRange        bool
+	RetryCounter          int
+}