Add Support for Custom ID Types

[Silent-Watcher]

Feature: Support Custom ID Types Beyond ObjectId

Description:
Currently, the user field is typed as ObjectId. Add support for custom ID types (Numbers, UUIDs, Strings) to accommodate different user identification systems.

Acceptance Criteria:

• Plugin option userIdType is added, accepting ObjectId, String, Number, etc.
• The reaction schema's user field type changes based on this option.
• All methods properly handle the specified ID type.
• TypeScript definitions are updated to support the generic type.
• Tests are added for different ID types.
• Add usage examples in docs