Resolve '@null' Issue in Facebook DMs

REQUEST_SUMMARY_V2 Problem - Current System: Currently, when Spur fetches Facebook messages, it encounters issues with the absence of usernames, resulting in the system sending "@null" in direct messages. Suggested Improvement: Develop a solution to handle cases where Facebook usernames are not available. Instead of defaulting to "@null," the system could use an alternative placeholder or skip the username insertion. This improvement aims to enhance the user experience by ensuring more coherent and professional communication. Submitted by Darshan Lathiya - Sudhati Expected behavior - Make the requested action possible without manual workaround - Ensure behavior is visible and predictable in product UI - Handle edge cases with clear user-facing errors Business impact - Reduces manual operational effort for teams - Improves consistency and customer experience - Helps teams move faster with fewer support escalations Legacy category: Improvement