feat: safe deletion, album/asset delete, trash, README update

- volume-aware deletion: read-only volumes remove DB only, writable
  volumes soft-delete to trash with configurable grace period
- trash page with restore, worker purge sweep (TRASH_RETENTION_DAYS)
- album delete endpoint + sidebar trash icon
- asset delete from timeline selection toolbar
- all listing queries exclude trashed assets (deleted_at IS NULL)
- timeline ordered by EXIF capture date, date-summary endpoint
- README rewritten with features, setup, full env var table

k-photos-frontend/components/album-sidebar.tsx

@@ -14,11 +14,12 @@ import {
 import { Button } from "@/components/ui/button"
 import { Input } from "@/components/ui/input"
 import { useAlbums } from "@/hooks/use-albums"
-import { ImageIcon, PlusIcon } from "lucide-react"
+import { toast } from "sonner"
+import { ImageIcon, PlusIcon, Trash2Icon } from "lucide-react"
 
 export function AlbumSidebar() {
   const pathname = usePathname()
-  const { albums, createAlbum } = useAlbums()
+  const { albums, createAlbum, deleteAlbum } = useAlbums()
   const [isCreating, setIsCreating] = useState(false)
   const [newTitle, setNewTitle] = useState("")
 
@@ -59,14 +60,31 @@ export function AlbumSidebar() {
         )}
         <SidebarMenu>
           {albums.map((album) => (
-            <SidebarMenuItem key={album.id}>
+            <SidebarMenuItem key={album.id} className="group/album">
               <SidebarMenuButton
                 asChild
                 isActive={pathname === `/albums/${album.id}`}
               >
                 <Link href={`/albums/${album.id}`}>
                   <ImageIcon className="h-4 w-4" />
-                  <span>{album.title}</span>
+                  <span className="flex-1">{album.title}</span>
+                  <Button
+                    variant="ghost"
+                    size="icon"
+                    className="h-5 w-5 opacity-0 group-hover/album:opacity-100"
+                    onClick={async (e) => {
+                      e.preventDefault()
+                      e.stopPropagation()
+                      try {
+                        await deleteAlbum(album.id)
+                        toast.success("Album deleted")
+                      } catch {
+                        toast.error("Failed to delete album")
+                      }
+                    }}
+                  >
+                    <Trash2Icon className="h-3 w-3" />
+                  </Button>
                 </Link>
               </SidebarMenuButton>
             </SidebarMenuItem>

k-photos-frontend/components/photo-grid.tsx

@@ -8,7 +8,7 @@ import { ImageViewer } from "./image-viewer"
 import { AddToAlbumDialog } from "./add-to-album-dialog"
 import { Button } from "@/components/ui/button"
 import { Spinner } from "@/components/ui/spinner"
-import { ImagePlusIcon, XIcon, CheckSquareIcon } from "lucide-react"
+import { ImagePlusIcon, XIcon, CheckSquareIcon, Trash2Icon } from "lucide-react"
 
 interface PhotoGridProps {
   groups: DateGroup[]
@@ -16,6 +16,7 @@ interface PhotoGridProps {
   hasMore: boolean
   onLoadMore: () => void
   onRemoveAsset?: (assetId: string) => void
+  onDeleteAssets?: (assetIds: string[]) => void
 }
 
 export function PhotoGrid({
@@ -24,6 +25,7 @@ export function PhotoGrid({
   hasMore,
   onLoadMore,
   onRemoveAsset,
+  onDeleteAssets,
 }: PhotoGridProps) {
   const sentinelRef = useRef<HTMLDivElement>(null)
   const [selectedIndex, setSelectedIndex] = useState<number | null>(null)
@@ -94,13 +96,26 @@ export function PhotoGrid({
           {onRemoveAsset && selectedIds.size > 0 && (
             <Button
               size="sm"
-              variant="destructive"
+              variant="secondary"
               onClick={() => {
                 selectedIds.forEach((id) => onRemoveAsset(id))
                 exitSelection()
               }}
             >
-              Remove
+              Remove from Album
+            </Button>
+          )}
+          {onDeleteAssets && selectedIds.size > 0 && (
+            <Button
+              size="sm"
+              variant="destructive"
+              onClick={() => {
+                onDeleteAssets(Array.from(selectedIds))
+                exitSelection()
+              }}
+            >
+              <Trash2Icon className="mr-1.5 h-3.5 w-3.5" />
+              Delete
             </Button>
           )}
           <Button size="sm" variant="ghost" onClick={exitSelection}>