feat: hide-from-views flag on folders

Adds a per-folder "hide from views" toggle so noisy subtrees
(screenshots, WhatsApp dumps, work archives) can be excluded from
cross-cutting views without losing indexing. Photos under a hidden
folder are still scanned, thumbnailed, embedded, OCR'd, face-
extracted — they just stop appearing in All Photos, Rated, Colors,
Map, Tags, People, Search, Duplicates, and the sidebar counts.
Navigating directly into the folder still shows every photo.

Schema (migration 0007_folder_hidden):
- folders.is_hidden   user-set toggle, default false
- photos.is_hidden    denormalized effective flag (true iff any
                      ancestor folder is hidden), indexed so cross-
                      cutting queries stay on the existing planner
                      paths

The denorm is maintained by two paths:
- The scanner walks the ancestry chain on insert, with a per-scan
  memoized cache so each folder is resolved once per scan.
- POST /api/v1/folders/{id}/hide flips folders.is_hidden and runs a
  WITH RECURSIVE CTE to recompute every folder's effective state in
  one query, then bulk-updates photos WHERE IS DISTINCT FROM. Runs
  in ~10 ms on a 13k-photo library.

Filters added (cross-cutting queries):
- /library/stats — every sidebar badge via a shared `visible` filter
- /photos (list) — only when neither folder_id nor heap_id is set;
  folder browse and heap browse always show everything
- /photos/map
- /library/duplicates/groups
- /folders/tree photo_count subquery
- /tags count_subq (drives Tags + People sidebar counts)
- services/duplicates.regroup_duplicates (so hidden dupes never
  contaminate the Duplicates view)
- services/search.hybrid_search — both semantic (pgvector) and FTS
  legs join photos so rankings don't include hidden results

Intentionally NOT filtered:
- /photos?folder_id=X and /photos?heap_id=X (user-intentional browse)
- /library/maintenance/pipeline-stats (tracks real worker state)
- cleanup service (disk-level ops, not views)

Frontend:
- sourceFolders.setHidden(id, hidden) API client method
- FolderTreeNode.is_hidden carried through the tree into TreeItem
- LeftSidebar kebab menu: "Hide from views" / "Show in views" with a
  mutation that invalidates folders, photos, stats, and tags caches
- Hidden folder rows swap the Folder icon for EyeOff and render the
  label italic/muted so the state is visible at a glance

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/layout/LeftSidebar.tsx

@@ -18,6 +18,8 @@ import {
   PanelLeftClose,
   Settings,
   Users,
+  Eye,
+  EyeOff,
 } from 'lucide-react'
 import clsx from 'clsx'
 import { sourceFolders, photos as photosApi, type FolderTreeNode } from '../../services/api'
@@ -46,6 +48,9 @@ interface TreeItem {
   count?: number
   children?: TreeItem[]
   type?: 'folder' | 'heap' | 'special'
+  /** For folder rows only: the user-set "hide from views" flag. Drives
+   *  the muted styling + eye-off badge + menu item label. */
+  isHidden?: boolean
 }
 
 interface LeftSidebarProps {
@@ -303,6 +308,32 @@ export function LeftSidebar({ onCollapse, onOpenSettings }: LeftSidebarProps) {
       toast.error('Create failed', e?.response?.data?.detail || e.message || 'Unknown error'),
   })
 
+  // Toggle folder hide-from-views. Invalidates every query that could
+  // include photos from the affected folder subtree — the sidebar
+  // tree (for the counts + badge), the photos timeline, library
+  // stats (sidebar badges), tags (count subquery), and duplicates
+  // (source for dup groups). All of these respect the new flag on
+  // the server side; the invalidation is just cache bust.
+  const toggleHiddenMutation = useMutation({
+    mutationFn: ({ id, hidden }: { id: string; hidden: boolean }) =>
+      sourceFolders.setHidden(id, hidden),
+    onSuccess: (data) => {
+      toast.success(
+        data.is_hidden ? 'Folder hidden' : 'Folder visible',
+        data.is_hidden
+          ? `${data.name} is now excluded from cross-cutting views`
+          : `${data.name} is back in cross-cutting views`
+      )
+      queryClient.invalidateQueries({ queryKey: ['folders'] })
+      queryClient.invalidateQueries({ queryKey: ['folders', 'tree'] })
+      queryClient.invalidateQueries({ queryKey: ['photos'] })
+      queryClient.invalidateQueries({ queryKey: LIBRARY_STATS_QUERY_KEY })
+      queryClient.invalidateQueries({ queryKey: ['tags'] })
+    },
+    onError: (e: any) =>
+      toast.error('Toggle failed', e?.response?.data?.detail || e.message || 'Unknown error'),
+  })
+
   const deleteFolderMutation = useMutation({
     mutationFn: ({ id, mode }: { id: string; mode: 'discard' | 'permanent' }) =>
       sourceFolders.delete(id, mode),
@@ -349,6 +380,7 @@ export function LeftSidebar({ onCollapse, onOpenSettings }: LeftSidebarProps) {
     icon: <Folder className="h-4 w-4" />,
     count: node.photo_count,
     type: 'folder',
+    isHidden: node.is_hidden,
     children: node.children.length > 0
       ? node.children.map(folderNodeToTreeItem)
       : undefined,
@@ -515,15 +547,23 @@ export function LeftSidebar({ onCollapse, onOpenSettings }: LeftSidebarProps) {
           )}
 
           {/* Item Icon — section headers drop their icon in favor of the
-           *  uppercase eyebrow label. */}
+           *  uppercase eyebrow label. Hidden folders swap the folder
+           *  icon for an EyeOff so the user sees the state at a glance
+           *  without hunting through the kebab menu. */}
           {item.icon && !isSectionHeader && (
             <span
               className={clsx(
                 'flex-shrink-0',
-                isSelected ? 'text-primary' : 'text-text-muted'
+                isSelected
+                  ? 'text-primary'
+                  : item.isHidden
+                    ? 'text-text-muted/60'
+                    : 'text-text-muted'
               )}
             >
-              <span className="[&>svg]:h-3.5 [&>svg]:w-3.5">{item.icon}</span>
+              <span className="[&>svg]:h-3.5 [&>svg]:w-3.5">
+                {item.isHidden ? <EyeOff className="h-4 w-4" /> : item.icon}
+              </span>
             </span>
           )}
 
@@ -553,7 +593,15 @@ export function LeftSidebar({ onCollapse, onOpenSettings }: LeftSidebarProps) {
               className="flex-1 rounded border border-border bg-bg px-1 py-0 text-[13px] text-text focus:border-primary focus:outline-none"
             />
           ) : (
-            <span className="flex-1 truncate">{item.label}</span>
+            <span
+              className={clsx(
+                'flex-1 truncate',
+                item.isHidden && !isSelected && 'italic text-text-muted/80'
+              )}
+              title={item.isHidden ? `${item.label} — hidden from views` : undefined}
+            >
+              {item.label}
+            </span>
           )}
 
           {/* Count Badge — fixed-width slot so counts line up in a column
@@ -629,6 +677,23 @@ export function LeftSidebar({ onCollapse, onOpenSettings }: LeftSidebarProps) {
                           setRenameDraft(item.label)
                         }}
                       />
+                      <FolderMenuItem
+                        icon={
+                          item.isHidden ? (
+                            <Eye className="h-3.5 w-3.5" />
+                          ) : (
+                            <EyeOff className="h-3.5 w-3.5" />
+                          )
+                        }
+                        label={item.isHidden ? 'Show in views' : 'Hide from views'}
+                        onClick={() => {
+                          setOpenMenuId(null)
+                          toggleHiddenMutation.mutate({
+                            id: folderId,
+                            hidden: !item.isHidden,
+                          })
+                        }}
+                      />
                       <div className="my-1 h-px bg-border" />
                       <FolderMenuItem
                         icon={<Trash2 className="h-3.5 w-3.5" />}