feat: add default highlight visibility settings

- Add defaultHighlightVisibilityNostrverse/Friends/Mine to UserSettings interface
- Add toggle controls in Settings page under Startup Preferences section
- Apply default visibility settings on app startup in Bookmarks component
- Users can now set which highlight levels (nostrverse/friends/mine) should be visible by default

src/components/Bookmarks.tsx

@@ -125,6 +125,12 @@ const Bookmarks: React.FC<BookmarksProps> = ({ relayPool, onLogout }) => {
   useEffect(() => {
     if (settings.defaultViewMode) setViewMode(settings.defaultViewMode)
     if (settings.showHighlights !== undefined) setShowHighlights(settings.showHighlights)
+    // Apply default highlight visibility settings
+    setHighlightVisibility({
+      nostrverse: settings.defaultHighlightVisibilityNostrverse !== false,
+      friends: settings.defaultHighlightVisibilityFriends !== false,
+      mine: settings.defaultHighlightVisibilityMine !== false
+    })
     // Always start with both panels collapsed on initial load
     // Don't apply saved collapse settings on initial load - let user control them
   }, [settings])

src/components/Settings.tsx

@@ -20,6 +20,9 @@ const DEFAULT_SETTINGS: UserSettings = {
   highlightColorNostrverse: '#9333ea',
   highlightColorFriends: '#f97316',
   highlightColorMine: '#ffff00',
+  defaultHighlightVisibilityNostrverse: true,
+  defaultHighlightVisibilityFriends: true,
+  defaultHighlightVisibilityMine: true,
 }
 
 interface SettingsProps {
@@ -256,6 +259,45 @@ const Settings: React.FC<SettingsProps> = ({ settings, onSave, onClose }) => {
                 <span>Start with highlights panel collapsed</span>
               </label>
             </div>
+
+            <div className="setting-group">
+              <label htmlFor="highlightVisibilityNostrverse" className="checkbox-label">
+                <input
+                  id="highlightVisibilityNostrverse"
+                  type="checkbox"
+                  checked={localSettings.defaultHighlightVisibilityNostrverse !== false}
+                  onChange={(e) => setLocalSettings({ ...localSettings, defaultHighlightVisibilityNostrverse: e.target.checked })}
+                  className="setting-checkbox"
+                />
+                <span>Show nostrverse highlights by default</span>
+              </label>
+            </div>
+
+            <div className="setting-group">
+              <label htmlFor="highlightVisibilityFriends" className="checkbox-label">
+                <input
+                  id="highlightVisibilityFriends"
+                  type="checkbox"
+                  checked={localSettings.defaultHighlightVisibilityFriends !== false}
+                  onChange={(e) => setLocalSettings({ ...localSettings, defaultHighlightVisibilityFriends: e.target.checked })}
+                  className="setting-checkbox"
+                />
+                <span>Show friends highlights by default</span>
+              </label>
+            </div>
+
+            <div className="setting-group">
+              <label htmlFor="highlightVisibilityMine" className="checkbox-label">
+                <input
+                  id="highlightVisibilityMine"
+                  type="checkbox"
+                  checked={localSettings.defaultHighlightVisibilityMine !== false}
+                  onChange={(e) => setLocalSettings({ ...localSettings, defaultHighlightVisibilityMine: e.target.checked })}
+                  className="setting-checkbox"
+                />
+                <span>Show my highlights by default</span>
+              </label>
+            </div>
           </div>
       </div>
     </div>

src/services/settingsService.ts

@@ -22,6 +22,10 @@ export interface UserSettings {
   highlightColorNostrverse?: string
   highlightColorFriends?: string
   highlightColorMine?: string
+  // Default highlight visibility toggles
+  defaultHighlightVisibilityNostrverse?: boolean
+  defaultHighlightVisibilityFriends?: boolean
+  defaultHighlightVisibilityMine?: boolean
 }
 
 export async function loadSettings(