fix(ci): commit newly added Crowdin translation files

The Crowdin sync workflow used `git diff --quiet` and `git commit -am`,
both of which only consider tracked files. New language files downloaded
by Crowdin (e.g. el-GR, th-TH) were therefore left untracked and silently
dropped on each run.

Switch the change check to `git status --porcelain` scoped to the
translation directories and stage them explicitly before committing so
new locales are included.

.github/workflows/crowdin.yml

@@ -41,7 +41,7 @@ jobs:
       - name: Check for changes
         id: check_changes
         run: |
-          if git diff --quiet; then
+          if [ -z "$(git status --porcelain pkg/i18n/lang frontend/src/i18n/lang)" ]; then
             echo "changes_exist=0" >> "$GITHUB_OUTPUT"
           else
             echo "changes_exist=1" >> "$GITHUB_OUTPUT"
@@ -51,7 +51,8 @@ jobs:
         run: |
           git config --local user.email "bot@vikunja.io"
           git config --local user.name "Frederick [Bot]"
-          git commit -am "chore(i18n): update translations via Crowdin"
+          git add pkg/i18n/lang frontend/src/i18n/lang
+          git commit -m "chore(i18n): update translations via Crowdin"
       - name: Push changes
         if: steps.check_changes.outputs.changes_exist != '0'
         uses: ad-m/github-push-action@master