Add reactions field to WAMessage

[muhammedaksam]

Is your feature request related to a problem? Please describe.

Currently, reactions to messages are stored in the _data field but not exposed as a first-class field in the WAMessage DTO. Clients need to manually parse the raw _data field to access reactions, which is undocumented, engine-specific, and error-prone.

Describe the solution you'd like

Add a reactions field to the WAMessage DTO that exposes message reactions across all engines. Each reaction should include:

• reaction - the emoji text (e.g., "👍")
• senderId - who sent the reaction
• timestamp - when the reaction was sent

Additionally, add a dedicated endpoint:

GET /api/{session}/chats/{chatId}/messages/{messageId}/reactions

Describe alternatives you've considered

1. Parsing reactions from _data directly in the client - works but is fragile and engine-dependent
2. Adding a separate getReactions() method to the session class - adds complexity without benefit since reactions can be bundled with messages

Additional context

• For WEBJS engine, this should use the existing message.getReactions() API from whatsapp-web.js
• For NOWEB engine, reactions are available in message.reactions
• For GOWS engine, reactions are in message.Reactions