Add online pinging and friendship verification features

Introduces OnlinePingingController and related integration/unit tests for user online status updates. Adds PingHandlerService with memory cache throttling, IPingHandlerService interface, and service registration. Implements VerifyFriendship service and interface for friendship validation, with exception handling. Refactors CurrentUserService for improved user ID extraction and testability. Updates ChatsHub to verify friendship before messaging. Cleans up MediaController and optimizes UsersRepository queries by removing unnecessary includes.

Govor.Application/Services/VerifierFriendship.cs

@@ -0,0 +1,55 @@
+using Govor.Application.Exceptions.VerifyFriendship;
+using Govor.Application.Interfaces;
+using Govor.Core.Models;
+using Govor.Core.Repositories.Friendships;
+using Microsoft.Extensions.Logging;
+
+namespace Govor.Application.Services;
+
+
+public class VerifyFriendship : IVerifyFriendship
+{
+    private readonly IFriendshipsRepository _friendshipsRepository;
+    private readonly ILogger<VerifyFriendship> _logger;
+    private const string FriendshipNotAcceptedError = "Friendship between user {0} and friend {1} does not exist or is not accepted.";
+
+    public VerifyFriendship(IFriendshipsRepository friendshipsRepository, ILogger<VerifyFriendship> logger = null)
+    {
+        _friendshipsRepository = friendshipsRepository ?? throw new ArgumentNullException(nameof(friendshipsRepository));
+        _logger = logger;
+    }
+
+    public async Task VerifyAsync(Guid targetUserId, Guid friendUserId)
+    {
+        if (targetUserId == Guid.Empty || friendUserId == Guid.Empty)
+        {
+            _logger?.LogWarning("Invalid user IDs provided: targetUserId={TargetUserId}, friendUserId={FriendUserId}", targetUserId, friendUserId);
+            throw new ArgumentException("User IDs cannot be empty.", nameof(targetUserId));
+        }
+
+        var friendships = await _friendshipsRepository.FindByUserIdAsync(targetUserId);
+        var friendship = friendships.Where(f => f.AddresseeId == friendUserId || f.RequesterId == friendUserId)?.FirstOrDefault();
+        
+        if (friendship == null || friendship.Status != FriendshipStatus.Accepted)
+        {
+            var errorMessage = string.Format(FriendshipNotAcceptedError, targetUserId, friendUserId);
+            _logger?.LogError(errorMessage);
+            throw new FriendshipException(errorMessage);
+        }
+
+        _logger?.LogInformation("Friendship verified successfully for targetUserId={TargetUserId}, friendUserId={FriendUserId}", targetUserId, friendUserId);
+    }
+
+    public async Task<bool> TryVerifyAsync(Guid targetUserId, Guid friendUserId)
+    {
+        try
+        {
+            await VerifyAsync(targetUserId, friendUserId);
+            return true;
+        }
+        catch (FriendshipException ex)
+        {
+            return false;
+        }
+    }
+}