nextcloud frontend

We concluded to integrate the frontend #10 (closed) as an iframe in a nextcloud app and allow registering any file in nextcloud. As a stub we could use the nextcloud app for OnlyOffice https://github.com/ONLYOFFICE/onlyoffice-nextcloud

There are some more signing apps out there:

• LibreSign https://faircloud.eu/nextcloud/index.php/settings/apps/installed/libresign - PDF signing nextcloud#124
• eID sign https://apps.nextcloud.com/apps/electronicsignatures - a service by eID easy (code https://github.com/eideasy/nextcloud-electronic-signatures-plugin has no license)
• SignLive https://faircloud.eu/nextcloud/index.php/settings/apps/installed/signlive - various signing levels https://www.intarsys.de/sites/default/files/Dokumente/Nextcloud%20App%20Sign%20Live%21%20Administrators%20Guide_1.pdf