docs(user): update dashboard and bookshelf instructions for sidebar UI

Dashboard:
- Customize Dashboard is opened from the icon button at the right end
  of the Library bar (next to Refresh), and requires a specific library
  selected rather than 'All Libraries'
- Library switching uses the Library dropdown in the bar below the top
  bar (includes 'All Libraries' with counts)
- Collection sections are shown/hidden from the Customize Dashboard
  toggles — the per-collection 'Show on Dashboard' setting is gone
- Mention the hover chevrons for scrolling carousels

Bookshelf:
- Saved filters: document the new toolbar buttons — Filters (opens the
  filter drawer with Apply Filters, Esc, and overlay-click close), Save,
  Load (Saved Filters dropdown with trash-icon delete), and Clear —
  replacing the emoji-labelled Save Filter / Saved Filters buttons
- Tag filtering: filters now live behind the Filters drawer on the All
  Books page

docs/user/dashboard.md

@@ -16,28 +16,27 @@ Smart sections are automatically generated based on your reading activity:
 
 ### User Collections
 
-Any collection marked with "Show on Dashboard" will appear as a section on your dashboard.
+Your collections appear as sections on the dashboard. To show or hide a collection's section:
 
-To enable a collection:
-
-1. Go to Collections
-2. Edit a collection
-3. Toggle "Show on Dashboard"
-4. Save
+1. Select the library in the **Library** bar
+2. Click the **Customize Dashboard** icon button
+3. Toggle the collection on or off
+4. Click "Save Changes"
 
 ### Customizing Your Dashboard
 
-1. Click the ⚙️ (gear icon) in the top-right
-2. **Drag sections** to reorder them
-3. **Toggle visibility** with the switches
-4. **Adjust items per section** (10-50 items)
-5. Click "Save Changes"
+1. In the **Library** bar below the top bar, select the library you want to customize (a specific library, not "All Libraries")
+2. Click the **Customize Dashboard** icon button at the right end of the Library bar (next to Refresh)
+3. **Drag sections** to reorder them
+4. **Toggle visibility** with the switches
+5. **Adjust items per section** (10-50 items)
+6. Click "Save Changes"
 
 Settings are saved per library.
 
 ### Library Switching
 
-Use the dropdown in the sticky header to switch between libraries. Each library has its own dashboard settings.
+Use the **Library** dropdown in the bar below the top bar to switch between libraries (including "All Libraries"). Each library has its own dashboard settings.
 
 ### Keyboard Navigation
 
@@ -45,6 +44,8 @@ Use the dropdown in the sticky header to switch between libraries. Each library
 - **Arrow Keys**: Scroll carousels horizontally
 - **Enter**: Open selected book
 
+Hovering a carousel shows chevron buttons on either side for scrolling.
+
 ### Touch Gestures (Mobile)
 
 - **Swipe**: Drag carousel left/right to scroll