feat: enhance profile editing with avatar support and UI adjustments

- Added AvatarPath to ProfileEditResult for user profile updates.
- Updated ProfileEditDialog to include avatar selection with a browse button.
- Increased dialog height to accommodate new avatar input fields.
- Implemented avatar file path handling in the profile edit dialog.

feat: introduce moderation features and user roles

- Added ServerRole enum to define user roles (Member, Mod, Admin, Owner).
- Extended User model to include role, mute, and ban status.
- Created ModerationController for user role assignment, kicking, banning, and muting.
- Implemented methods in IChatBroadcaster and SignalRBroadcaster for user moderation actions.
- Updated database schema with new columns for user roles and moderation states.

fix: ensure muted users cannot send messages

- Added mute status checks in ChatService to prevent message sending for muted users.
- Updated user presence and status handling to reflect role changes and moderation actions.

chore: update constants for ASCII art rendering

- Introduced AsciiArtHeightHalfBlock constant for improved ASCII art rendering.

src/EchoHub.Core/Models/User.cs

@@ -11,6 +11,10 @@ public class User
     public string? AvatarAscii { get; set; }
     public UserStatus Status { get; set; } = UserStatus.Online;
     public string? StatusMessage { get; set; }
+    public ServerRole Role { get; set; } = ServerRole.Member;
+    public bool IsMuted { get; set; }
+    public DateTimeOffset? MutedUntil { get; set; }
+    public bool IsBanned { get; set; }
     public DateTimeOffset CreatedAt { get; set; } = DateTimeOffset.UtcNow;
     public DateTimeOffset LastSeenAt { get; set; } = DateTimeOffset.UtcNow;
 }