feat(go): add realtime pipeline observability

go/vehicle-gateway/internal/realtime/model.go

@@ -37,6 +37,24 @@ type OnlineStatus struct {
 	TTLSeconds     int64               `json:"ttl_seconds"`
 }
 
+type OnlineListQuery struct {
+	Protocol envelope.Protocol `json:"protocol,omitempty"`
+	Limit    int               `json:"limit"`
+	Offset   int               `json:"offset"`
+}
+
+type ProtocolPipelineSummary struct {
+	Protocol     envelope.Protocol `json:"protocol"`
+	IndexedCount int64             `json:"indexed_count"`
+	OnlineCount  int64             `json:"online_count"`
+	LatestSeenMS int64             `json:"latest_seen_ms"`
+}
+
+type PipelineSummary struct {
+	Protocols []ProtocolPipelineSummary `json:"protocols"`
+	UpdatedMS int64                     `json:"updated_ms"`
+}
+
 type Config struct {
 	OnlineTTL time.Duration
 }