Remove survey abstractions from ui/questions.go

[blsmth]

Summary

Remove all survey abstraction code from ui/questions.go and drop the survey dependency entirely.

Details

• Complexity: Low (but must be the last issue completed)
• Remove QuestionExtra, BooleanOptionProxy, MultiLineValueProxy, StringValueProxy, AskQuestions(), and the survey import
• Run go mod tidy to drop survey from go.mod
• Only after all other survey-to-huh issues are complete

Dependencies

• Requires ALL other survey-to-huh issues to be completed first

Checklist

• Remove QuestionExtra type
• Remove BooleanOptionProxy type
• Remove MultiLineValueProxy type
• Remove StringValueProxy type
• Remove AskQuestions() function
• Remove survey import
• Run go mod tidy to clean up go.mod / go.sum
• Verify go build ./... and go test ./... pass