Refactor and update types and handlers

- README changes: removed 'as const' annotation and note.
- Connector changes: dispatched event for commands in gateway.
- Updated processor type guard for command handlers.
- Removed readonly from CommandHandler types in handler definitions.
- Test adjustments: updated demo tests to reliable command registration.

src/services/processor.ts

@@ -180,7 +180,7 @@ export class Processor {
         has: (event: string) => this.handlers[HandlerType.Interactions].has(event) ?? this.handlers[HandlerType.Interactions].get(event)?.length! > 0
     };
 
-    static isCommandHandler = (handler: Handler): handler is CommandHandler<readonly ApplicationCommandOption[]> => {
+    static isCommandHandler = (handler: Handler): handler is CommandHandler<ApplicationCommandOption[]> => {
         if (typeof handler === 'object') {
             return 'args' in handler && Trait.execute in handler && handler instanceof CommandHandler;
         } else {