add log position tracking

local/utl/tracking/position_tracker.go

@@ -0,0 +1,54 @@
+package tracking
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+)
+
+type LogPosition struct {
+	LastPosition int64    `json:"last_position"`
+	LastRead     string   `json:"last_read"`
+}
+
+type PositionTracker struct {
+	positionFile string
+}
+
+func NewPositionTracker(logPath string) *PositionTracker {
+	// Create position file in same directory as log file
+	dir := filepath.Dir(logPath)
+	base := filepath.Base(logPath)
+	positionFile := filepath.Join(dir, "."+base+".position")
+	
+	return &PositionTracker{
+		positionFile: positionFile,
+	}
+}
+
+func (t *PositionTracker) LoadPosition() (*LogPosition, error) {
+	data, err := os.ReadFile(t.positionFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// Return empty position if file doesn't exist
+			return &LogPosition{}, nil
+		}
+		return nil, err
+	}
+
+	var pos LogPosition
+	if err := json.Unmarshal(data, &pos); err != nil {
+		return nil, err
+	}
+
+	return &pos, nil
+}
+
+func (t *PositionTracker) SavePosition(pos *LogPosition) error {
+	data, err := json.Marshal(pos)
+	if err != nil {
+		return err
+	}
+
+	return os.WriteFile(t.positionFile, data, 0644)
+}