Add weekly database dump workflow

[xrendan]

Summary

• Adds automated weekly database dumps every Monday at 2 AM UTC
• Uploads dumps as GitHub artifacts with 30-day retention
• Excludes users table for privacy/security

Implementation Details

• Uses GitHub Actions scheduled workflow (cron)
• Connects directly to production database via DATABASE_URL secret
• Uses GitHub API directly (no Ruby gems) for artifact upload
• Includes automatic cleanup of artifacts older than 28 days
• Can be manually triggered via workflow_dispatch

Setup Required

• Add DATABASE_URL secret in repository settings

Test plan

• Manually trigger workflow to test database connection
• Verify dump file is created without users table
• Confirm artifact upload succeeds
• Check artifact can be downloaded from Actions tab

🤖 Generated with Claude Code