feat: Add Create Channel dialog and related events

- Introduced CreateChannelDialog for user to create new channels with name and topic.
- Added OnCreateChannelRequested event in MainWindow for channel creation.
- Enhanced EchoHubConnection with OnReconnected event for connection state handling.
- Updated EchoHubDbContext to use application base directory for SQLite database path.
- Integrated Serilog for logging in EchoHub.Server.
- Refactored database initialization and migration logic into DatabaseSetup class.
- Implemented FirstRunSetup to ensure appsettings.json and generate JWT secret if needed.
- Updated appsettings files to configure Serilog logging.
- Enhanced error handling and logging in ChatHub methods for better traceability.

src/EchoHub.Server/Data/EchoHubDbContext.cs

@@ -15,7 +15,8 @@ public class EchoHubDbContext(DbContextOptions<EchoHubDbContext> options) : DbCo
     {
         if (!optionsBuilder.IsConfigured)
         {
-            optionsBuilder.UseSqlite("Data Source=echohub.db");
+            var dbPath = Path.Combine(AppContext.BaseDirectory, "echohub.db");
+            optionsBuilder.UseSqlite($"Data Source={dbPath}");
         }
     }