Add confirm_or_exit() function to lib/common.sh to eliminate duplicated
confirmation dialog code in prepare_db.sh.
Before: Two 10-line case statements with identical logic
After: Two single-line function calls
The function provides consistent behavior:
- Displays the question with Y/N options
- Returns 0 on Y/y (continue execution)
- Exits with error on any other input
This follows DRY principle and ensures all confirmation prompts
behave identically across the codebase.
7b1ce9cc5a