ui improvements

There are still a few UI improvements left:
- move files/folder in the repository
- select a folder for uploading a file
- use flowchart.js as webjar
- unmock getTargetGraphs in DAO.js
- add the ability to rename the opened workflow
- add ui shortcuts for move, delete, new,...
- add the ability to upload a target graph over the ui
- view the content of a file in the repository

Start by splitting the seven UI improvements into separate, concrete tasks and inspect DAO.js for the getTargetGraphs item. Trace the existing repository, workflow, upload, and shortcut entry points before choosing a focused scope. Done means the selected UI behavior works and has corresponding verification, but no tests or additional files are named in the issue.

Written by the indexing model from the issue text.