ci(flatpak): stop the Gradle daemon before reclaiming its home (#7347)

.github/workflows/verify-flatpak.yml

@@ -122,8 +122,11 @@ jobs:
           echo "- URLs captured: $(jq length flatpak-sources.json)" >> "$GITHUB_STEP_SUMMARY"
 
       # flatpak-builder re-downloads the whole closure anyway; a second copy just eats disk.
+      # The daemon from the previous step still writes into this home, so stop it first.
       - name: Reclaim the isolated Gradle home
-        run: rm -rf "$RUNNER_TEMP/flatpak-gradle-home"
+        run: |
+          ./gradlew -Dgradle.user.home="$RUNNER_TEMP/flatpak-gradle-home" --stop
+          rm -rf "$RUNNER_TEMP/flatpak-gradle-home"
 
       - name: Clone the Flathub packaging repo
         run: |