Major changes to the file disk subsystem:
- Each FileDisk now gets a unique Laravel disk name (disk_{id}) instead
of temp_{driver}, fixing the bug where multiple local disks with
different roots overwrote each other's config.
- Move disk registration logic from FileDisk model to FileDiskService
(registerDisk, getDiskName). Model keeps only getDecodedCredentials
and a deprecated setConfig() wrapper.
- Add Disk Assignments admin UI (File Disk tab) with three purpose
dropdowns: Media Storage, PDF Storage, Backup Storage. Stored as
settings (media_disk_id, pdf_disk_id, backup_disk_id).
- Backup tab now uses the assigned backup disk instead of a per-backup
dropdown. BackupsController refactored to use BackupService which
centralizes disk resolution. Removed stale 4-second cache.
- Add local_public disk to config/filesystems.php so system disks
are properly defined.
- Local disk roots stored relative to storage/app/ with hint text
in the admin modal explaining the convention.
- Fix BaseModal watchEffect -> watch to prevent infinite request
loops on the File Disk page.
- Fix string/number comparison for disk purpose IDs from settings.
- Add safeguards: prevent deleting disks with files, warn on
purpose change, prevent deleting system disks.
