v0.6.6

Database Backup & Search Improvements

🗄️ Database Backup

• Scheduled backup: SQLite VACUUM INTO snapshots on a configurable schedule
• List & download: API to list existing backups and download them as attachments
• Settings UI: Enable toggle, backup path, keep-count, and file list with download links

🔍 Search Improvements

• Time range search

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Full Changelog: v0.6.5...v0.6.6