ci(android): chmod +x gradlew in-step (runner drops exec bit)

Setting the git executable bit (100755) wasn't enough: this Gitea/act
runner's checkout doesn't preserve file modes, so './gradlew' still failed
with 'Permission denied' (exit 126). chmod the wrapper in the run step
itself so the build is independent of how checkout handles modes.

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

.gitea/workflows/pr-checks.yml

@@ -58,5 +58,9 @@ jobs:
           restore-keys: |
             gradle-${{ runner.os }}-
 
+      # chmod defensively: this runner's checkout doesn't preserve the git
+      # executable bit, so `./gradlew` alone fails with "Permission denied".
       - name: Lint, test, assemble debug
-        run: ./gradlew --no-daemon lint test assembleDebug
+        run: |
+          chmod +x ./gradlew
+          ./gradlew --no-daemon lint test assembleDebug