feat: add collapse-on-article-open setting

- Add collapseOnArticleOpen setting (default: true)
- Position as first setting in settings panel
- Auto-collapse bookmark bar when user opens an article
- User can disable this behavior in settings

src/components/Bookmarks.tsx

@@ -133,6 +133,12 @@ const Bookmarks: React.FC<BookmarksProps> = ({ relayPool, onLogout }) => {
     setSelectedUrl(url)
     setReaderLoading(true)
     setReaderContent(undefined)
+    
+    // Collapse sidebar if setting is enabled (default true)
+    if (settings.collapseOnArticleOpen !== false) {
+      setIsCollapsed(true)
+    }
+    
     try {
       const content = await fetchReadableContent(url)
       setReaderContent(content)

src/components/Settings.tsx

@@ -37,6 +37,19 @@ const Settings: React.FC<SettingsProps> = ({ settings, onSave, onClose, isSaving
         </div>
 
         <div className="settings-content">
+          <div className="setting-group">
+            <label htmlFor="collapseOnArticleOpen" className="checkbox-label">
+              <input
+                id="collapseOnArticleOpen"
+                type="checkbox"
+                checked={localSettings.collapseOnArticleOpen !== false}
+                onChange={(e) => setLocalSettings({ ...localSettings, collapseOnArticleOpen: e.target.checked })}
+                className="setting-checkbox"
+              />
+              <span>Collapse bookmark bar when opening an article</span>
+            </label>
+          </div>
+
           <div className="setting-group">
             <label htmlFor="defaultViewMode">Default View Mode</label>
             <select

src/services/settingsService.ts

@@ -9,6 +9,7 @@ import { Account } from 'applesauce-accounts'
 const SETTINGS_IDENTIFIER = 'com.dergigi.boris.user-settings'
 
 export interface UserSettings {
+  collapseOnArticleOpen?: boolean
   defaultViewMode?: 'compact' | 'cards' | 'large'
   showUnderlines?: boolean
   sidebarCollapsed?: boolean