fix: fetch commit subject via Gitea API instead of git log

Notification job had no checkout step so git log always failed,
producing "Commit info unavailable". Now uses the existing
API_GITEA_TOKEN and gitea.sha context to fetch the commit message
from the Gitea API directly.

Also raises default coverage threshold in python-checks to 80%.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/notifications.yml

@@ -147,7 +147,11 @@ jobs:
             exit 0
           fi
 
-          COMMIT_SUBJECT="$(git log -1 --pretty=%s 2>/dev/null || echo 'Commit info unavailable')"
+          COMMIT_SUBJECT="$(curl -fsS \
+            -H "Authorization: Bearer ${{ secrets.API_GITEA_TOKEN }}" \
+            "${{ gitea.server_url }}/api/v1/repos/${{ gitea.repository }}/git/commits/${{ gitea.sha }}" \
+            | python3 -c "import json,sys; d=json.load(sys.stdin); print(d.get('RepoCommit',{}).get('message','').split('\n')[0])" \
+            2>/dev/null || echo 'Commit info unavailable')"
           RUN_URL="${{ gitea.server_url }}/${{ gitea.repository }}/actions/runs/${{ gitea.run_number }}"
 
           cat <<EOF >/tmp/ntfy-payload.json