feat(runtime): track node lifecycle and QUIC link state

backend/shared/MoShiro.Protocol/Rpc/NodeRuntimeStatus.cs

@@ -0,0 +1,23 @@
+using System.Text.Json.Serialization;
+
+namespace MoShiro.Protocol;
+
+/// <summary>Live process/measurement state. Enrollment approval remains a separate node status.</summary>
+[JsonConverter(typeof(JsonStringEnumConverter<NodeRuntimeStatus>))]
+public enum NodeRuntimeStatus
+{
+    [JsonStringEnumMemberName("initializing")]
+    Initializing,
+    [JsonStringEnumMemberName("running")]
+    Running,
+    [JsonStringEnumMemberName("probe_paused")]
+    ProbePaused,
+    [JsonStringEnumMemberName("maintenance")]
+    Maintenance,
+    [JsonStringEnumMemberName("stopping")]
+    Stopping,
+    [JsonStringEnumMemberName("offline")]
+    Offline,
+    [JsonStringEnumMemberName("updating")]
+    Updating,
+}