TEN-30: Implement trash management service and Tauri commands

[nicolas-agentzero]

Summary

Implements TEN-30 trash management in the codebase with a new core TrashService and Tauri commands for desktop integration.

What was implemented

Core (tentacle-core)

• Added new module: core/src/trash.rs
• Added and exported pub mod trash; in core/src/lib.rs
• Implemented TrashService APIs:
  • list_trash(documents_folder)
  • recover_item(documents_folder, trash_path, strategy)
  • delete_permanently(documents_folder, trash_path)
  • clear_trash(documents_folder)
  • run_auto_cleanup(documents_folder) (30-day retention)
  • get_trash_stats(documents_folder)
• Implemented path safety validation for trash_path (relative-only, no traversal)
• Implemented conflict-safe recovery strategy:
  • original_location (fails if destination exists)
  • with_suffix (restores as name (1).md, etc)
• Added payloads for UI/backend integration:
  • TrashedItem
  • TrashListResult
  • TrashStats
  • RecoveryResult

Desktop/Tauri bridge (frontend/src-tauri)

Added commands in frontend/src-tauri/src/lib.rs:

• list_trash_items
• recover_trash_item
• delete_trash_item_permanently
• clear_trash_items
• run_trash_auto_cleanup
• get_trash_stats

And registered all of them in the Tauri invoke handler.

Tests

Added unit tests in core/src/trash.rs for:

• listing trash items
• restoring to original path
• suffix recovery on destination conflict

Notes

• This PR covers backend/service + Tauri command surface.
• Frontend trash UI wiring can now be built on top of these commands.