Integrated, working.

This integrates the liteq, and it prevents duplicates in a way that
matches my use-case.

I might try and push things back out to a separate module, but for now,
this will do.

Makefile

@@ -3,4 +3,5 @@ test: generate
 	
 generate:
 	cd internal/domain64 ; make generate
-	cd internal/liteq ; sqlc generate
+	cd internal/liteq ; sqlc generate
+	cd internal/liteq ; make schema-const