Enhanced Abstract Submission Limits & Custom Messaging

Context: Previously, the function restricting the number of submissions per user (Max_Abstract_Submissions) was applied visually within the participant's profile. However, we identified and resolved a loophole where users could bypass this restriction by accessing the public form directly.

With this new update: 

• Absolute email validation: The system now performs a check at the database level at the exact moment the form is saved. If the entered email address has already reached the maximum limit allowed for that project, the submission is automatically blocked, ensuring event rules are strictly maintained.
• Customisable messaging: A new field has been added to the admin panel (My Page Parameters > Max Abstract Submissions Message). This allows organisers to draft their own alert message when a user reaches their submission limit, significantly improving the end-user experience.