feat: add source and target database type fields

Add source_db_type and target_db_type to the migration config so the same binary can drive any supported direction.

internal/app/models/main.go

@@ -11,12 +11,17 @@ type Batch struct {
 	RetryCounter int
 }
 
-type Partition struct {
-	Id                    uuid.UUID
-	ParentId              uuid.UUID
-	LowerLimit            int64
-	UpperLimit            int64
-	IsLowerLimitInclusive bool
-	ShouldUseRange        bool
-	RetryCounter          int
+type PartitionRange struct {
+	Min            int64
+	Max            int64
+	IsMinInclusive bool
+	IsMaxInclusive bool
+}
+
+type Partition struct {
+	Id           uuid.UUID
+	ParentId     uuid.UUID
+	Range        PartitionRange
+	HasRange     bool
+	RetryCounter int
 }