Behavior: Creates a new user session record or updates the last activity date on an existing session for the specified content record. Captures browser type, OS, device type, and user email. This endpoint is used as a heartbeat mechanism to track active content viewers.

Authorization: Requires authentication with a valid user ID.

Side Effects: Creates or updates a content user session record in the database.

Error Scenarios: Returns 400 Bad Request if the authenticated user does not have a valid user ID.