Fix issues with Journal handling

Implement basic database
Handle startup events
only send events after the most recent LoadGame

Pulsar/Features/Backpack/BackpackService.cs

@@ -0,0 +1,46 @@
+namespace Pulsar.Features.Backpack;
+
+using Observatory.Framework.Files;
+
+public interface IBackpackService : IJournalHandler<BackpackFile>;
+
+public class BackpackService(IOptions<PulsarConfiguration> options, IEventHubContext hub, ILogger<BackpackService> logger) : IBackpackService
+{
+    public async Task<BackpackFile> Get()
+    {
+        var filePath = Path.Combine(options.Value.JournalDirectory, FileName);
+
+        if (!FileHelper.ValidateFile(filePath))
+        {
+            return new BackpackFile();
+        }
+
+        await using var file = File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
+        var backpack = await JsonSerializer.DeserializeAsync<BackpackFile>(file);
+        if (backpack != null) return backpack;
+
+        logger.LogWarning("Failed to deserialize backpack file {File}", filePath);
+        return new BackpackFile();
+    }
+
+    public async Task HandleFile(string path, CancellationToken token = new ())
+    {
+        if (!FileHelper.ValidateFile(path))
+        {
+            return;
+        }
+
+        var file = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
+        var backpack = await JsonSerializer.DeserializeAsync<BackpackFile>(file, cancellationToken: token);
+
+        if (backpack == null)
+        {
+            logger.LogWarning("Failed to deserialize backpack {FilePath}", file);
+            return;
+        }
+
+        await hub.Clients.All.BackpackUpdated(backpack);
+    }
+
+    public string FileName => FileHandlerService.BackpackFileName;
+}