feat(clean): add --trash option to move cleaned files to Trash instead of deleting

[spider-yamet]

Summary

Adds an option to move cleaned files to the system Trash instead of permanently removing them, so users can recover items if needed.

Closes #439

Changes

• lib/core/file_ops.sh
  • Add safe_move_to_trash() that uses macOS Finder (osascript) to move paths to Trash.
  • When MOLE_USE_TRASH=1, safe_remove() tries trash first and falls back to rm if trash fails (e.g. headless or permission).
  • Dry-run messages show "Would move to Trash" when --trash is used.
• bin/clean.sh
  • Add --trash / -t flag and set MOLE_USE_TRASH=1.
  • Update footer hint to mention --trash.
• lib/core/help.sh
  • Document --trash, -t in clean help.

Usage

• mo clean --dry-run — preview (no changes)
• mo clean --dry-run --trash — preview move to Trash
• mo clean --trash — clean and move items to Trash
• mo clean — default: permanent removal (unchanged)

Notes

• Trash is only used for user-level paths that go through safe_remove(). safe_sudo_remove() (system paths) is unchanged and still permanently removes.
• On non-macOS or when osascript is unavailable, the code falls back to permanent removal.

Testing

• tests/cli.bats: mo clean --help shows --trash.
• tests/clean_core.bats: mo clean --dry-run --trash does not delete files.
• tests/core_safe_functions.bats: safe_remove with MOLE_USE_TRASH=1 removes the file (trash or fallback).

[tw93]

@spider-yamet Thanks for the suggestion and for taking the time to describe the use case.

After reviewing this, we will not plan this feature for now.

Reasoning:

1. mo clean is designed for immediate disk reclaim, while moving files to Trash does not reliably free space right away.
2. We already provide a safe preview path with --dry-run, plus protection controls via --whitelist.
3. Adding a Trash mode introduces behavior ambiguity across environments (interactive/headless) and increases maintenance complexity.

So for now, we keep the current safety model: preview first (--dry-run), then clean with explicit user control (--whitelist).

We may revisit this in the future if we can provide a strict and fully predictable Trash-only workflow.