[HoungDev]

Summary

• add rename --prefix while preserving image as the default
• validate prefixes as safe filename components across Windows, macOS, and Linux
• carry custom destinations through preview, apply, JSON schema v1, manifests, and undo
• update the changelog, README, JSON reference, transcript, and generated demo

Safety and compatibility

Invalid prefixes are rejected before files or manifests change. Validation covers empty or padded values, path separators, control and Windows-invalid characters, reserved device names, trailing periods, and filename-component length limits. Existing commands without --prefix retain the image_N naming format, and manifests remain version 1 because they already store concrete operations.

Verification

• ruff check .
• ruff format --check .
• pytest — 85 passed, 94.02% coverage
• README demo rebuilt deterministically and inspected visually
• pip-audit — no known vulnerabilities
• wheel and sdist built successfully; twine check passed
• built wheel installed in a fresh virtual environment; custom preview/apply/undo and invalid-prefix entry-point smoke checks passed

Closes #17