chore: Remove unused fields in FPL and DEP structs

The code changes remove the unused `SurveillanceEquipment` field in the `FPL` struct and the `TelegramCategory` field in the `DEP` struct. These fields are no longer needed and can be safely removed. This commit improves code cleanliness and reduces unnecessary complexity.

internal/domain/dep.go

@@ -52,7 +52,7 @@ Description: This field contains any additional relevant information. It is opti
 */
 // DEP 电报体中的起飞报文结构
 type DEP struct {
-	TelegramCategory     string `json:"telegram_category"`           // 电报类别
+	Category             string `json:"category"`                    // 电报类别
 	AircraftID           string `json:"aircraft_id"`                 // 航空器识别标志
 	SSRModeAndCode       string `json:"ssr_mode_and_code,omitempty"` // SSR 模式及编码（可选）
 	DepartureAirport     string `json:"departure_airport"`           // 起飞机场
@@ -65,7 +65,7 @@ type DEP struct {
 
 // Validate validates the DEP struct fields
 func (d *DEP) Validate() error {
-	if d.TelegramCategory == "" {
+	if d.Category == "" {
 		return fmt.Errorf("telegram category is required")
 	}
 	if d.AircraftID == "" {

internal/domain/dep_test.go

@@ -13,7 +13,7 @@ var _ = Describe("DEP", func() {
 
 	BeforeEach(func() {
 		original = DEP{
-			TelegramCategory:     "DEP",
+			Category:             "DEP",
 			AircraftID:           "ABCD1234",
 			SSRModeAndCode:       "A1234",
 			DepartureAirport:     "JFK",
@@ -45,7 +45,7 @@ var _ = Describe("DEP", func() {
 
 		It("should fail validation for missing required fields", func() {
 			invalidDEP := DEP{
-				TelegramCategory: "DEP",
+				Category: "DEP",
 				// AircraftID is missing
 				DepartureAirport:     "JFK",
 				DepartureTime:        "150405",

internal/domain/fpl.go

@@ -57,7 +57,6 @@ type FPL struct {
 	AlternateAirport        string `json:"alternate_airport,omitempty"`   // 目的地备降机场（可选）: Alternate airport (e.g., 'ZBYN').
 	OtherInfo               string `json:"other_info,omitempty"`          // 其他信息（可选）: Other information.
 	SupplementaryInfo       string `json:"supplementary_info,omitempty"`  // 补充信息（可选）: Supplementary information.
-	SurveillanceEquipment   string `json:"surveillance_equipment"`        // 监视设备信息: Surveillance equipment information (e.g., 'SDE3FGHIJ4J5M1RWY').
 	EstimatedArrivalTime    string `json:"estimated_arrival_time"`        // 预计到达时间: Estimated time of arrival (e.g., '0153').
 	PBN                     string `json:"pbn"`                           // 性能导航: Performance-based navigation equipment (e.g., 'A1B2B3B4B5D1L1').
 	NavigationEquipment     string `json:"navigation_equipment"`          // 导航设备: Navigation equipment (e.g., 'NAV/ABAS').
@@ -98,9 +97,6 @@ func (f *FPL) Validate() error {
 	if f.DestinationAndTotalTime == "" {
 		return fmt.Errorf("destination and total time is required")
 	}
-	if f.SurveillanceEquipment == "" {
-		return fmt.Errorf("surveillance equipment is required")
-	}
 	if f.EstimatedArrivalTime == "" {
 		return fmt.Errorf("estimated arrival time is required")
 	}

internal/domain/fpl_test.go

@@ -27,7 +27,6 @@ var _ = Describe("FPL", func() {
 			AlternateAirport:        "SFO",     // Example alternate airport
 			OtherInfo:               "Test flight",
 			SupplementaryInfo:       "Supplementary information",
-			SurveillanceEquipment:   "SDE3FGHIJ4J5M1RWY",
 			EstimatedArrivalTime:    "0153", // Example estimated arrival time
 			PBN:                     "A1B2B3B4B5D1L1",
 			NavigationEquipment:     "NAV/ABAS",