Implement trash bin with soft delete and recovery

[Ditract]

Description

Add a trash bin system that allows users to safely delete and recover notes/folders without permanently losing data.

Features

• Soft delete notes/folders (mark as deleted in DB instead of removing)
• Add "Trash" section to view deleted items
• Add "Restore" option to recover items from trash
• Add "Delete permanently" option for individual items
• Automatic permanent deletion after X days (configurable, default: 30 days)
• (Optional) "Empty trash" button to delete all items at once

Technical considerations

• Database: Add deleted_at timestamp field (nullable)
• Filter out soft-deleted items from normal queries
• Create scheduled job/cron for automatic cleanup
• Consider storage implications for retention period