Creates a new note entry associated with a specific contact.

Required Fields:

• note: The body text of the note (max 1000 characters).

Behavior:

• Returns 201 with empty body.
• Returns 400 if required fields are missing or fail validation constraints.
• Returns 401 if the caller is not authenticated.
• Returns 404 if the contactId does not exist.

This endpoint is rate limited. Use the RateLimit-* response headers to check current limits and remaining quota.