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.Server/Data/EchoHubDbContext.cs

@@ -34,6 +34,7 @@ public class EchoHubDbContext : DbContext
             entity.Property(u => u.NicknameColor).HasMaxLength(7);
             entity.Property(u => u.AvatarAscii).HasMaxLength(10000);
             entity.Property(u => u.StatusMessage).HasMaxLength(100);
+            entity.Property(u => u.Role).HasConversion<int>();
         });
 
         modelBuilder.Entity<Channel>(entity =>