feat(ui): (optional) Protect starred media from accidental deletion

[FloeHetling]

• new settings option: "Protect starred media"
• when protection is enabled, following features will be active:

• there will be impossible to delete an image or video with Star mark. If "Confirm on delete" is enabled, a warning toast will appear on said attempt (silent otherwise)
• upon attempting to use "Delete Board, Images & Videos" option, additional confirmation will be issued if said board has at least one media item with Star mark
• upon agreeing, marked media will be kept and moved to "Uncategorized", while the board and unmarked media will be deleted
• upon attempting to delete a group selected of images or videos, media marked with Star will not be touched and a toast about protection status will be thrown if "Confirm on delete" is enabled (silent otherwise)
• same behavior should be expected from "Delete All Uncategorized Images/Videos" option
• protection is disabled by default and existing deletion clients keep the old behavior

Summary

• new settings option: "Protect starred media"
• the option is disabled by default, so the usual deletion behavior is left unchanged
• when protection is enabled, following features will be active:

• there will be impossible to delete an image or video with Star mark. If "Confirm on delete" is enabled, a warning toast will appear on said attempt (silent otherwise)
• upon attempting to use "Delete Board, Images & Videos" option, additional confirmation will be issued if said board has at least one image or video with Star mark
• upon agreeing to delete such board, the board and all unmarked media will be deleted. Starred images and videos will be kept and moved to "Uncategorized"
• upon attempting to delete a group selected of images or videos, media marked with Star will not be touched and a toast about protection status will be thrown if "Confirm on delete" is enabled (silent otherwise)
• same behavior should be expected from "Delete All Uncategorized Images/Videos" option

• the protection is enforced by backend image and video services. Existing clients keep the old behavior unless they explicitly request starred media protection
• failed deletion and media skipped due to protection are reported separately, so frontend selection and cached media are only cleaned for items that were actually deleted

Related Issues / Discussions

This is a complete re-work of #8406, done from scratch relying on latest unified gallery, video deletion and multi-user board changes.

QA Instructions

Careful. This test implies some of the images and videos can or will be eventually lost. For safety of your artwork, consider using testing environment

• have some images and videos to start test with, 10x media items should be enough
• enable the "Protect starred media" option in your app Settings
• mark 2 images, select 3 images, 2 of which are marked and 1 is not. Press the Delete key or use Delete icon in viewer. Expected behavior: one unmarked artwork should be deleted, while both marked images should be left untouched
• repeat the previous step with videos. Expected behavior: only unmarked videos should be deleted
• enable "Confirm on delete" and attempt to delete a marked image or video. Expected behavior: the media should stay untouched and a warning toast should appear. Disable "Confirm on delete" and repeat the attempt: the media should still be protected, but without the warning toast
• create a new board and move one marked image and one marked video there. Add one unmarked image and one unmarked video. Attempt to delete that board using "Delete Board, Images & Videos" option. Expected behavior: additional confirmation should be issued about deleting the board with starred media
• agree to the additional confirmation. Expected behavior: the board and both unmarked items should be gone. The marked image and video should be left untouched and moved to "Uncategorized"
• use "Delete All Uncategorized Images/Videos" from "Uncategorized" board context menu. Confirm the deletion. Expected behavior: unmarked media should be deleted, while the marked image and video should be left untouched
• disable "Protect starred media" and delete the remaining marked items. Expected behavior: the usual deletion behavior should be restored and starred media should be deleted

Merge Plan

No special merge plan should be needed. The feature was completely re-done from scratch on top of latest main instead of reusing the old implementation. Generated OpenAPI schema and frontend API types are included in the PR.

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• !Changes to a redux slice have a corresponding migration
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)