[Feature] Granular folder/library permissions for Partner Sharing and External Libraries

I have searched the existing feature requests, both open and closed, to make sure this is not a duplicate request. • Yes The feature Hi Immich team and community, First of all, thank you so much for your incredible work on Immich—it is truly an amazing project! Before opening this thread, I searched through the existing discussions regarding folder-based permissions and granular sharing controls. I noticed that similar ideas have been brought up by other users in the past, but I wasn't entirely sure if these proposals are currently planned, under active consideration, or held back due to architectural trade-offs. Because this is a crucial feature for setups like mine, I would like to softly re-open the topic with a specific real-world use case to highlight why it would make a huge difference. My Use Case & Challenge I manage a large historical archive of 100,000+ photos structured in directories on a NAS (e.g., /volume/photos/Family, /volume/photos/RAW, …