feat(core): add metrics history storage interface and point model

src/Vantage.Core/History/IMetricsStore.cs

@@ -0,0 +1,23 @@
+using Vantage.Core.Models;
+
+namespace Vantage.Core.History;
+
+public interface IMetricsStore
+{
+    Task RecordAsync(MetricSample sample, CancellationToken cancellationToken = default);
+
+    Task RecordManyAsync(IEnumerable<MetricSample> samples, CancellationToken cancellationToken = default);
+
+    Task RecordHostMetricsAsync(string hostId, HostMetrics metrics, CancellationToken cancellationToken = default);
+
+    Task<IReadOnlyList<MetricPoint>> QueryAsync(
+        string hostId,
+        string metric,
+        DateTimeOffset from,
+        DateTimeOffset to,
+        CancellationToken cancellationToken = default);
+
+    Task<int> PruneOlderThanAsync(DateTimeOffset cutoff, CancellationToken cancellationToken = default);
+
+    Task<long> CountAsync(CancellationToken cancellationToken = default);
+}

src/Vantage.Core/History/MetricNames.cs

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+namespace Vantage.Core.History;
+
+public static class MetricNames
+{
+    public const string Cpu = "cpu";
+    public const string Memory = "memory";
+    public const string Disk = "disk";
+    public const string Load1 = "load1";
+    public const string Load5 = "load5";
+    public const string Load15 = "load15";
+    public const string NetworkRx = "networkRx";
+    public const string NetworkTx = "networkTx";
+
+    public static readonly IReadOnlyList<string> All = new[]
+    {
+        Cpu, Memory, Disk, Load1, Load5, Load15, NetworkRx, NetworkTx
+    };
+}

src/Vantage.Core/History/MetricPoint.cs

@@ -0,0 +1,5 @@
+namespace Vantage.Core.History;
+
+public readonly record struct MetricPoint(DateTimeOffset Timestamp, double Value);
+
+public readonly record struct MetricSample(string HostId, string Metric, DateTimeOffset Timestamp, double Value);