Development-related redundant files

Could you please check the following files? They might be redundant, and you can reduce the Flatpak size by a few MB.

```
./include
./share/bash-completion
./share/man
*.la
*.a
```

See: https://github.com/flathub-infra/vorarbeiter/actions/runs/33128897099/job/98713707649#step:21:50

Review ./include, ./share/bash-completion, ./share/man, and the *.la and *.a files alongside the linked vorarbeiter job at step 21:50. Confirm which files are unnecessary in the Flatpak build, remove them from packaging, and verify that the resulting artifact is smaller.

Written by the indexing model from the issue text.