Update GitHub Actions workflows to handle invalid-users.json #542

Description

In PR #535, we updated the analyze-inactivity.js script to distinguish 404 permanent failures from temporary API errors, which routes the missing/invalid users to invalid-users.json.
However, we missed updating the GitHub Actions workflow YAML files to handle this new behavior correctly.

Required Changes

1. .github/workflows/analyze-inactivity.yml:
   The invalid-users.json file needs to be staged and committed alongside inactive-users.json. The git add command in the "Commit and Push to Data Repo" step should be updated to include it.
2. .github/workflows/sync-leaderboard.yml:
   The invalid-users.json file must be reset from the staging area (git reset -q invalid-users.json) in the "Stage changes" step before committing. This ensures that any merge conflicts arise between the two workflows.