Added ChangeLog

Added change log to track updates to the database, for easier pinging
from Syncer client.

FreeTubeSync/EndPoints/PingEndpoint.cs

@@ -0,0 +1,29 @@
+using FreeTubeSync.Database;
+using FreeTubeSync.Model.Database;
+
+namespace FreeTubeSync.EndPoints;
+
+public static class PingEndpoint
+{
+    public static void MapPingEndpoints(this WebApplication app)
+    {
+        var group = app.MapGroup("ping");
+        group.MapGet("/", async (CancellationToken token) =>
+        {
+            await Task.Delay(10);
+            var dict = new { AppVersion = "0.1.3" };
+            return Results.Ok(dict);
+        });
+
+        group.MapGet("/lastUpdated", async (DataContext dbContext, CancellationToken token) =>
+        {
+            var log = await dbContext.GetLatestChangeAsync(token);
+            
+            if (log == null)
+                return Results.NotFound();
+            
+            var dict = new { LastUpdated = log.ChangeTime };
+            return Results.Ok(dict);
+        });
+    }
+}

FreeTubeSync/Model/Database/ChangeLog.cs

@@ -0,0 +1,9 @@
+namespace FreeTubeSync.Model.Database;
+
+public class ChangeLog
+{
+    public int Id { get; set; }
+    public string TableName { get; set; } = string.Empty;
+    public string ChangeType { get; set; } = string.Empty;
+    public DateTime ChangeTime { get; set; } = DateTime.MinValue;
+}