InvoiceNinja Web App modification -- 2

Hi, There is opensource software found at: [login to view URL] or [login to view URL] I am self-hosting an older version of the Docker version of the software ([login to view URL]) on Linux server. Specifically, I still have v.4 of the software and not the newer v.5 (actually, v. 4.18) [login to view URL] (the non-alpine version) The non-docker version can be downloaded from: [login to view URL] I'd like to add the following feature: The current 32-character link generated for each invoice ("View in Portal") does not expire unless the invoice is deleted. I'd like to be able to enter a date in a field on the invoice page after which the Portal link is deleted/expired, unless I extend or enter a new date. Alternatively (but not as useful to me), I'd like to have a list of all links and allow me to manually inactivate a specific link so that recipient is no longer able to access the invoice. Both options would be even better, if not too time consuming. Please see attached screenshot - Large hand-drawn green arrow towards the top third of the image is where the link is - "View in Portal". The additional field I need for the link or portal expiration date is hand-drawn in light blue box just to the right of the "View in Portal". Field should be similar to the 2 fields below named "Invoice Date" and "Due Date". This date field is the only modification to the software I need, and obviously the link ("View in Portal") should not work after this date unless the date is extended. Finally, given that this is an "aftermarket" modification, if we agree to proceed with the aforementioned project, I would need to have a log of which path/files were modified and what the modified lines are for my verification of the code modifications, or just creating a fork in a private GitHub repository and then making commits to that. Thank you in advance.