This reverts commit 49cb74e3.

Squashed commit of the following:

commit 8f68fe66
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Wed Feb 5 09:11:41 2025 +0100

    user guide on sparse free-slip. Fix CI config.

commit 12935ac4
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Tue Feb 4 16:52:26 2025 +0100

    Add Free-Slip Pipe Test case.

commit ed6f686c
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Tue Feb 4 13:13:15 2025 +0100

    fix freeslip indexing bug. test suite WIP.

commit ec4f2e93
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Mon Feb 3 16:39:51 2025 +0100

    freeslip is still irregularily segfaulting. I dont know why.

commit f5b4f809
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Mon Feb 3 15:14:43 2025 +0100

    irregular free-slip implementation

Update pystencils & pystencils-sfg dependencies. Update user manual examples. Add CI task to build examples.

Squashed commit of the following:

commit 6a1da92e
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Tue Jan 21 17:22:45 2025 +0100

    short amendmend to the docs

commit 7a97e846
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Tue Jan 21 17:18:17 2025 +0100

    update user manual

commit 974ad9a1
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Tue Jan 21 16:11:49 2025 +0100

    Add sparse sweeps + test case

commit de84e76d
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Thu Jan 16 13:59:57 2025 +0100

    fix name of nox session

commit 3920b82d
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Thu Jan 16 13:56:25 2025 +0100

    Fix CI yaml. Add notes on Python env.

commit f96049fc
Merge: 227d81f4 f797e579
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Thu Jan 16 13:39:30 2025 +0100

    Merge branch 'fhennig/examples' of i10git.cs.fau.de:da15siwa/sfg-walberla into fhennig/examples

commit 227d81f4
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Thu Jan 16 13:39:27 2025 +0100

    rename examples to user_manual. Set up CI task for building it.

commit f797e579
Author: Frederik Hennig <frederik.hennig@fau.de>
Date:   Thu Jan 16 13:26:08 2025 +0100

    Extend PrepareSFG CMake module

...

refactor hbb boundaries to take a blockforest ref, instead of a shared_ptr. Extend SweepProperties to accept custom initializers.

 - correct ghost layer handling in sweeps
 - add actual field pointer swaps after kernel
 - add grouping of vectorial params
 - rename `classes` to `api`; extend waLBerla api reflection