Move latest developments up the chain into production

See merge request !239

Testing fixes and stabilization
Test improvement / speed up
PostgreSQL side container for building

Fix use of WEBP in production (file formats are all 3 letters, but WEBP is 4 letters, breaking the limited varchar(3)

Closes #97

See merge request !237

Resolve "Logout leading to HTTP error 405" and add new tests to catch it next time

Closes #95

See merge request !236

Ensure master has the latest fixes from devel included

See merge request !235

Pull in latest developments

See merge request !230

Update CI config for sec. scanning

See merge request !229

Set sast config 1

See merge request !228

Ensure working CI setup that passes the CI test

See merge request !227

Reverse mr !121, since we have a b0kren ci/cd setup it seems

See merge request !225

Configure SAST in `.gitlab-ci.yml`, creating this file if it does not already exist

See merge request !224

Merge latest devel branch

See merge request !223

Update produciton with latest fixes and project setup

See merge request !222

Closes issue #91

Closes #91

See merge request !221

Update testing

See merge request !220

These files are not relevant at all, but helped during research,
development, debugging. Hence, don't throw them away, but move them a
bit more out of sight.