Fix a bunch of papercuts

[benjie]

• 🚨 TypeScript v5 is now the minimum supported version, because we use const type parameters
• 🚨 Improves types in various places, in particular lambda and list
• 🚨 @omit on a column now also omits the related foreign key constraints, like it did in V4
• 💅 Improved error logging
• ✨ Reintroduce step assertions with more flexible function-based approach
• ✨ Pro-actively detect async plans and throw an error during schema construction
• 💅 Don't compress class names in the bundle (we need them for useful debugging output/plan diagrams!)
• 💅 When multiple grafast or pg-sql2 instances are present, warn the user

Fixes #240