Closes#519
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
* **New Features**
* Notification destinations can now be tested even when disabled, enabling configuration validation before activation
* **Improvements**
* Discord notification formatting parameters optimized for enhanced message delivery
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
* refactor: move migrations to new structure
* refactor: convert all findMany to new structure
* fix(backups-schedule): missing null matching for last backup status
* chore: move root lib to server
* feat(db): add support for multiple users and organizations
* feat: backfill entities with new organization id
* refactor: filter all backend queries to surface only organization specific entities
* refactor: each org has its own restic password
* test: ensure organization is created
* chore: pr feedbacks
* refactor: filter by org id in all places
* refactor: download restic password from stored db password
* refactor(navigation): use volume id in urls instead of name
* feat: disable registrations
* refactor(auth): bubble up auth error to hono
* refactor: use async local storage for cleaner context sharing
* refactor: enable user registration vs disabling it
* test: multi-org isolation
* chore: final cleanup
* refactor(startup): ensure entities always use the latest configuration schema
* refactor: await config updates to avoid race condition on later mount
* refactor: use short ids to allow changing the name of volumes & repos
* refactor: address PR feedbacks
* fix: make short_id non null after initial population
