Closes#590
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
* **Tests**
* Enhanced test coverage for backup pattern handling and anchoring
* Added end-to-end scenarios validating include patterns, exclusion patterns, and exclude-if-present functionality
* **Refactor**
* Updated pattern processing logic to improve relative path resolution for backup patterns
* Improved asynchronous handling in backup initialization workflow
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Allows users to pass arbitrary restic flags via a new advanced section in the create/edit schedule form. Includes DB migration, schema update, DTO, service, and restic command changes.
When a selected subfolder had the exact same name as its parent volume
mount, the `path.relative` check falsely identified the subfolder path
as an absolute path already inside the volume. This caused the entire
volume root to be backed up instead of the intended subfolder.
Closes#250
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
* **Bug Fixes**
* Improved handling of backup patterns when folder names match volume names.
* Enhanced error handling for snapshot deletion operations.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
