Good practices !
✅ on my personal projects

• Documentation in the same repo as the code ✅
• Mechanisms for creating test data
• Rock solid database migrations
• Templates for new projects and components
• Automated code formatting ✅
• Tested, automated process for new development environments ✅
• Automated preview environments ✅

As a result, to avoid downtime you need to design every schema change with this in mind. The process needs to be:

1. Design a new schema change that can be applied without changing the application code that uses it.
2. Ship that change to production, upgrading your database while keeping the old code working.
3. Now ship new application code that uses the new schema.
4. Ship a new schema change that cleans up any remaining work—dropping columns that are no longer used, for example.