Feature: Add --structure flag for RESTORE to control output path style

[djdarcy]

Summary

Currently, RESTORE mirrors the backup's directory structure (respecting the original --rel, --abs, --flat choice). Users should have control over the restored structure independent of how the backup was organized.

Proposed Feature

Add a --structure (or -str) flag to RESTORE with the following options:

Value	Behavior
dst	Default - Mirror the destination/backup structure (current behavior)
orig	Restore to original source paths as recorded in the manifest
rel	Use relative path structure
abs	Use absolute path structure (with drive letter as directory)
flat	Flatten all files into a single directory

Usage Examples

# Current behavior (default: dst)
preserve RESTORE --src backup/ --dst restored/
# Result: mirrors backup structure

# Restore to original locations recorded in manifest
preserve RESTORE --src backup/ --structure orig

# Restore with absolute path structure
preserve RESTORE --src backup/ --dst restored/ --structure abs
# Result: restored/C/data/file.txt

# Restore flat
preserve RESTORE --src backup/ --dst restored/ --structure flat
# Result: restored/file.txt (all files in root)

Technical Considerations

• Manifest already stores original source paths - this enables orig mode
• orig mode should work without --dst (restores directly to original locations)
• Other modes require --dst to avoid overwriting original files
• Conflict handling (--on-conflict) should apply to all structure modes

Context

This complements the existing path preservation options (--rel, --abs, --flat) used during COPY/MOVE by giving equivalent control during RESTORE operations.

See discussion in README.md section "Understanding RESTORE --dst Behavior" for current behavior documentation.