Add deploy to `dev.iscsc.fr` workflow

[ctmbl]

completes #53 , see https://github.com/iScsc/blog.iscsc.fr/pull/53#issuecomment-2118290000 to understand

see https://dev.iscsc.fr/

• [x] create a workflow to deploy a PR to this endpoint
• [x] make the workflow need a maintainer approval (to avoid deployment on EVERY pull request but on-demand) see https://github.com/iScsc/blog.iscsc.fr/pull/53#issuecomment-2118018664
• [x] update/add GH secrets to take into account the new build artifacts hierarchy
• [x] carefully check the build folders consistency across host, containers, documentation and GH workflow
• [x] artificially modify the dev.iscsc.fr webpage to disclaim about its in-devlopment content and give the PR info/commit
• [ ] reate a recurrent workflow that will delete dev.iscsc.fr content and replace it by a default "empty" webpage
• [x] BUG: use run and not up with docker cvompose to use -e --> fixed b154a02
• [x] BUG: must overwrite --baseURL to dev.iscsc.fr !! --> fixed b154a02

[ctmbl]

originally posted here: https://github.com/iScsc/blog.iscsc.fr/pull/53#issuecomment-2118018664

To require manual approval of the deployment of a PR to dev.iscsc.fr I could have used https://github.com/marketplace/actions/manual-workflow-approval but it creates an issue every time such as https://github.com/liquibase/liquibase/issues/5740 which isn't suitable in our case

I preferred to use the GitHub way with Environments and created a deployment-dev environment whihc requires my approval to allow the workflow to run:

• https://github.com/iScsc/blog.iscsc.fr/settings/environments
• https://docs.github.com/en/actions/deployment/targeting-different-environments/using-environments-for-deployment#using-an-environment
• f045da5