[Feature]: MigrateCommand should confirm before overwriting files

[Splatcrafter]

AI REVIEWED

Module: cli
File: cli/command/MigrateCommand.java (~line 640-662)
Severity: Medium

Problem / Motivation

Files are overwritten silently without confirmation. Backup files use a predictable .bak extension that gets overwritten by subsequent runs. No way for users to opt out of destructive operations.

Proposed Solution

1. Add --force / --no-confirm flag for non-interactive usage
2. Generate timestamped backups: file.json.bak.20260320T123456Z
3. Prompt user before overwriting when running interactively