[Feature] Support nested albums (album hierarchy)

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request. • Yes The feature Currently, all albums in Immich exist on a single level. I would like to request support for nested albums (sub-albums), allowing users to organize albums in a hierarchical structure. Example: Family ├── Trip 1 ├── Trip 2 └── Birthday Instead of having all albums displayed at the root level: Family Trip 1 Trip 2 Birthday This would greatly improve organization for users with large photo collections and many albums. Use cases • Organize family-related albums under a "Family" parent album • Group travel albums by region, year, or category • Create project-based album structures • Reduce clutter in the album list when managing hundreds of albums Suggested behavior • Allow creating albums inside existing albums • Support navigation through parent and child albums …