feat: add server logs functionality with role-based access and system channel management

- Introduced a new migration to add the IsSystem column to the Channels table.
- Updated the DbContext model snapshot to reflect the new IsSystem property.
- Enhanced the ChannelService to manage system channels, including creation, visibility control, and protection against deletion.
- Implemented ServerLogsService to handle live server logging, including reading from log files and managing access based on user roles.
- Created ServerLogsSink to queue log events for streaming to the live log room.
- Developed ServerLogsStreamService to stream log events to clients in real-time.
- Added configuration options for server logs in appsettings.
- Implemented comprehensive unit tests for channel service system channel behavior and server logs functionality.

src/EchoHub.Tests/Irc/TestHelpers.cs

@@ -280,6 +280,12 @@ internal sealed class FakeChannelService : IChannelService
 
     public Task<(bool Success, string? Error, bool PasswordRequired)> EnsureChannelMembershipAsync(Guid userId, string channelName, string? password = null) =>
         Task.FromResult(MembershipResult);
+
+    public ChannelDto? SystemChannelToReturn { get; set; }
+
+    public Task<ChannelDto> EnsureSystemChannelAsync(string channelName, string? topic = null) =>
+        Task.FromResult(SystemChannelToReturn ?? new ChannelDto(
+            Guid.NewGuid(), channelName, topic, false, 0, DateTimeOffset.UnixEpoch, false, false, true));
 }
 
 /// <summary>