Add volume history to platform summary

src/Managing.Application/Grains/PlatformSummaryGrain.cs

@@ -229,6 +229,20 @@ public class PlatformSummaryGrain : Grain, IPlatformSummaryGrain, IRemindable
         return Task.FromResult(_state.State.TotalPositionCount);
     }
 
+    public Task<List<VolumeHistoryPoint>> GetVolumeHistoryAsync()
+    {
+        var historyPoints = _state.State.DailySnapshots
+            .OrderBy(s => s.Date)
+            .Select(s => new VolumeHistoryPoint
+            {
+                Date = s.Date,
+                Volume = s.TotalVolume
+            })
+            .ToList();
+
+        return Task.FromResult(historyPoints);
+    }
+
     // Event handlers for immediate updates
     public async Task UpdateActiveStrategyCountAsync(int newActiveCount)
     {
@@ -374,6 +388,16 @@ public class PlatformSummaryGrain : Grain, IPlatformSummaryGrain, IRemindable
 
     private PlatformSummaryViewModel MapToViewModel(PlatformSummaryGrainState state)
     {
+        // Generate volume history from daily snapshots
+        var volumeHistory = state.DailySnapshots
+            .OrderBy(s => s.Date)
+            .Select(s => new VolumeHistoryPoint
+            {
+                Date = s.Date,
+                Volume = s.TotalVolume
+            })
+            .ToList();
+
         return new PlatformSummaryViewModel
         {
             TotalAgents = state.TotalAgents,
@@ -397,6 +421,9 @@ public class PlatformSummaryGrain : Grain, IPlatformSummaryGrain, IRemindable
             PositionCountByAsset = state.PositionCountByAsset ?? new Dictionary<Ticker, int>(),
             PositionCountByDirection = state.PositionCountByDirection ?? new Dictionary<TradeDirection, int>(),
 
+            // Volume history for charting (last 30 days)
+            VolumeHistory = volumeHistory,
+
             // Metadata
             LastUpdated = state.LastUpdated,
             Last24HourSnapshot = state.LastSnapshot