- deploy.yml: add missing BLUESKY_HANDLE env var to Build site step
- deploy.yml: fix GITHUB_USERNAME secret name (was GH_USERNAME)
- mastodonFeed.js: read MASTODON_URL first, fall back to MASTODON_INSTANCE
- mastodonFeed.js: add early-return guard when instance/user vars are empty
- mastodonFeed.js: also accept MASTODON_USERNAME as fallback for MASTODON_USER
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>