feat(auth): enhance security with token hashing and sync integration

- Add token hash fields to Master and Key models for indexed lookups
- Implement SyncService integration in admin and master handlers
- Update master key validation with backward-compatible digest lookup
- Hash child keys in database and store token digests for Redis sync
- Add master metadata sync to Redis for balancer validation
- Ensure backward compatibility with legacy rows during migration

internal/service/token.go

@@ -49,11 +49,18 @@ func (s *TokenService) ValidateToken(ctx context.Context, token string) (*TokenI
 
 	// 2. Get master metadata from Redis
 	masterKey := fmt.Sprintf("auth:master:%d", masterID)
-	masterEpochStr, err := s.rdb.HGet(ctx, masterKey, "epoch").Result()
+	masterData, err := s.rdb.HGetAll(ctx, masterKey).Result()
 	if err != nil {
-		return nil, fmt.Errorf("failed to get master epoch: %w", err)
+		return nil, fmt.Errorf("failed to get master metadata: %w", err)
 	}
-	masterEpoch, _ := strconv.ParseInt(masterEpochStr, 10, 64)
+	if len(masterData) == 0 {
+		return nil, errors.New("master metadata not found")
+	}
+	masterStatus := masterData["status"]
+	if masterStatus != "" && masterStatus != "active" {
+		return nil, errors.New("master is not active")
+	}
+	masterEpoch, _ := strconv.ParseInt(masterData["epoch"], 10, 64)
 
 	// 3. Core Epoch Validation
 	if issuedAtEpoch < masterEpoch {