fix: correct rainyunServer JSON field names to match actual API (PascalCase)

internal/provider/rainyun/server.go

@@ -16,15 +16,15 @@ type ServerService struct {
 // rainyunServer mirrors the Rainyun RCS API JSON fields (PascalCase).
 type rainyunServer struct {
 	ID         int    `json:"ID"`
-	Name       string `json:"name"`
+	HostName   string `json:"HostName"`
 	Status     string `json:"status"`
-	IP         string `json:"ip"`
-	VCPU       int    `json:"vcpu"`
+	MainIPv4   string `json:"MainIPv4"`
+	CPU        int    `json:"CPU"`
 	Memory     int    `json:"memory"`
 	Disk       int    `json:"disk"`
-	OS         string `json:"os"`
-	Region     string `json:"zone_name"`
-	ExpireDate int64  `json:"ExpDate"` // Unix timestamp
+	OsName     string `json:"OsName"`
+	Zone       string `json:"Zone"`
+	ExpireDate int64  `json:"ExpDate"`
 }
 
 func (s *ServerService) List(ctx context.Context) ([]provider.Server, error) {
@@ -90,14 +90,14 @@ func toServer(r rainyunServer) provider.Server {
 	expire := time.Unix(r.ExpireDate, 0)
 	return provider.Server{
 		ID:       fmt.Sprintf("%d", r.ID),
-		Name:     r.Name,
+		Name:     r.HostName,
 		Status:   r.Status,
-		IP:       r.IP,
-		CPU:      r.VCPU,
+		IP:       r.MainIPv4,
+		CPU:      r.CPU,
 		Memory:   r.Memory,
 		Disk:     r.Disk,
-		OS:       r.OS,
-		Region:   r.Region,
+		OS:       r.OsName,
+		Region:   r.Zone,
 		ExpireAt: expire,
 		Raw:      r,
 	}

internal/provider/rainyun/server_test.go

@@ -18,15 +18,16 @@ func TestServerList(t *testing.T) {
 			"data": map[string]any{
 				"Records": []map[string]any{
 					{
-						"ID":          12001,
-						"name":        "web-server",
-						"status":      "running",
-						"ip":          "1.2.3.4",
-						"vcpu":        2,
-						"memory":      4096,
-						"disk":        50,
-						"os":          "Ubuntu 22.04",
-						"ExpDate":     1756656000,
+						"ID":        12001,
+						"HostName":  "web-server",
+						"status":    "running",
+						"MainIPv4":  "1.2.3.4",
+						"CPU":       2,
+						"memory":    4096,
+						"disk":      50,
+						"OsName":    "Ubuntu 22.04",
+						"Zone":      "cn-sy1",
+						"ExpDate":   1756656000,
 					},
 				},
 				"TotalRecords": 1,