Prevent Self-Reactions Option

[Silent-Watcher]

Feature: Add Option to Prevent Self-Reactions

Description:
Add a new plugin option preventSelfReactions: boolean. When enabled, it throws an error if a user tries to react to a document they own (comparing userId with a document's authorId or similar). This requires a new option to specify the path to the author's ID field on the schema.

Acceptance Criteria:

• New plugin option: preventSelfReactions: boolean.
• New plugin option: authorIdPath: string (e.g., 'author').
• The react method checks if userId equals the document's authorIdPath value.
• If they match and preventSelfReactions is true, an error is thrown.
• Tests are added for this new validation.
• Add usage examples in docs