Add Redis support for SignalR backplane and caching

- Introduced Redis configuration in appsettings.json to enable SignalR backplane functionality.
- Updated Program.cs to conditionally configure SignalR with Redis if a connection string is provided.
- Added Redis connection service registration in ApiBootstrap for distributed scenarios.
- Included necessary package references for StackExchange.Redis and Microsoft.Extensions.Caching.StackExchangeRedis in project files.
- Implemented password masking for Redis connection strings to enhance security.

src/Managing.Bootstrap/ApiBootstrap.cs

@@ -510,9 +510,56 @@ public static class ApiBootstrap
         services.AddTransient<ICacheService, CacheService>();
         services.AddSingleton<ITaskCache, TaskCache>();
 
+        // Redis (for SignalR backplane and other distributed scenarios)
+        services.AddRedis(configuration);
+
         return services;
     }
 
+    private static IServiceCollection AddRedis(this IServiceCollection services, IConfiguration configuration)
+    {
+        // Check if Redis is configured
+        // Priority: ConnectionStrings:Redis (can be set via ConnectionStrings__Redis env var) > REDIS_URL env var
+        var redisConnectionString = configuration.GetConnectionString("Redis") 
+                                  ?? configuration["REDIS_URL"];
+
+        if (!string.IsNullOrWhiteSpace(redisConnectionString))
+        {
+            Console.WriteLine($"✅ Redis configured: {MaskRedisPassword(redisConnectionString)}");
+            
+            // Register generic Redis connection service for various use cases
+            // (SignalR backplane, distributed caching, pub/sub, etc.)
+            services.AddSingleton<IRedisConnectionService, RedisConnectionService>();
+        }
+        else
+        {
+            Console.WriteLine("ℹ️  Redis not configured - running in single-instance mode");
+            
+            // Register a no-op Redis service that returns null connections
+            services.AddSingleton<IRedisConnectionService>(sp => 
+                new RedisConnectionService(configuration, sp.GetRequiredService<ILogger<RedisConnectionService>>()));
+        }
+
+        return services;
+    }
+
+    private static string MaskRedisPassword(string connectionString)
+    {
+        if (connectionString.Contains("password=", StringComparison.OrdinalIgnoreCase))
+        {
+            var parts = connectionString.Split(',');
+            for (int i = 0; i < parts.Length; i++)
+            {
+                if (parts[i].Trim().StartsWith("password=", StringComparison.OrdinalIgnoreCase))
+                {
+                    parts[i] = "password=***";
+                }
+            }
+            return string.Join(",", parts);
+        }
+        return connectionString;
+    }
+
     private static IServiceCollection AddWorkers(this IServiceCollection services, IConfiguration configuration)
     {
         if (configuration.GetValue<bool>("WorkerNotifyBundleBacktest", false))