Summary

• Handle nullable content in all social media publishers to prevent TypeError crashes in production
• Add per-platform validation: YouTube requires title, Threads/Facebook text-only posts require content, X requires text or media
• Change PublishToSocialPlatform job to catch \Throwable instead of \Exception
• Remove unused Threads reply scopes
• Add null content tests for Instagram, Threads, Facebook, X, and YouTube publishers

Test plan

• Verify all 666 tests pass
• Test publishing with empty caption on Instagram, Facebook, Threads
• Test publishing on YouTube without content (should show error)
• Test publishing on X with only media (should work)