Merge branch 'main' of https://gitea.federated.computer/Federated_Computer/coredesktop

Brings in the shellcheck lint and bats tests. Both sides fixed the same
shellcheck warnings; this keeps the remote's versions of 20-aur.sh,
80-gnome-extensions.sh and .shellcheckrc, which silence false positives
per line rather than for the whole repo.

The Gitea workflow now runs make lint, so it checks the same scripts as
the Makefile, and the README points contributors at make check. The test
helper's REPO, used only by the .bats files, is marked for shellcheck,
and the update test expects the pull to be fast-forward only.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.gitea/workflows/shellcheck.yml

@@ -1,4 +1,4 @@
-# Check every bash script with shellcheck (settings in .shellcheckrc)
+# Check every bash script with shellcheck: make lint (settings in .shellcheckrc)
 name: shellcheck
 
 on: [push, pull_request]
@@ -12,11 +12,6 @@ jobs:
         run: |
           SUDO=$(command -v sudo || true)
           $SUDO apt-get update -q
-          $SUDO apt-get install -y -q shellcheck
+          $SUDO apt-get install -y -q shellcheck make
       - name: Run shellcheck
-        run: |
-          git ls-files -z | while IFS= read -r -d '' f; do
-            [ -L "$f" ] && continue
-            case "$f" in *.sh|*.conf) echo "$f"; continue ;; esac
-            head -n 1 "$f" | grep -q '^#!.*bash' && echo "$f"
-          done | xargs -d '\n' shellcheck -S warning
+        run: make lint