refactor: address code review findings across all projects

Apply comprehensive fixes from code reviews including:
- Extract shared utilities (SqlFormatHelper, CellValueConverter, DbDestinationBase)
- Add interface abstractions (IAuthenticationService, IDatabaseMigrator, IMisQueryBuilder)
- Implement SecureStore for encrypted secrets storage
- Fix error handling with proper HTTP status codes and logging
- Optimize double enumeration in DevEtlRegistry
- Add DataSync.Dev README for developer onboarding
- Extract filter panel base classes to reduce duplication
- Update code review docs to mark all issues as fixed

NEW/src/JdeScoping.Api/Hubs/StatusHub.cs

@@ -1,5 +1,6 @@
 using JdeScoping.Core.ViewModels;
 using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Logging;
 
 namespace JdeScoping.Api.Hubs;
@@ -9,17 +10,17 @@ namespace JdeScoping.Api.Hubs;
 /// </summary>
 public class StatusHub : Hub
 {
-    private static StatusUpdateViewModel _cachedStatus = new()
-    {
-        Message = "Unknown",
-        Timestamp = DateTime.UtcNow
-    };
+    private const string StatusCacheKey = "StatusHub_CachedStatus";
 
+    private readonly IMemoryCache _cache;
     private readonly ILogger<StatusHub> _logger;
+    private readonly TimeProvider _timeProvider;
 
-    public StatusHub(ILogger<StatusHub> logger)
+    public StatusHub(IMemoryCache cache, ILogger<StatusHub> logger, TimeProvider timeProvider)
     {
+        _cache = cache;
         _logger = logger;
+        _timeProvider = timeProvider;
     }
 
     /// <summary>
@@ -29,7 +30,7 @@ public class StatusHub : Hub
     /// <param name="statusUpdate">Status update to broadcast</param>
     public async Task SetStatus(StatusUpdateViewModel statusUpdate)
     {
-        _cachedStatus = statusUpdate;
+        _cache.Set(StatusCacheKey, statusUpdate);
         await Clients.All.SendAsync("statusUpdate", statusUpdate);
         _logger.LogDebug("Status updated: {Message}", statusUpdate.Message);
     }
@@ -40,7 +41,11 @@ public class StatusHub : Hub
     /// <returns>The most recent status update</returns>
     public StatusUpdateViewModel GetCachedStatus()
     {
-        return _cachedStatus;
+        return _cache.GetOrCreate(StatusCacheKey, _ => new StatusUpdateViewModel
+        {
+            Message = "Unknown",
+            Timestamp = _timeProvider.GetUtcNow().DateTime
+        })!;
     }
 
     /// <summary>