feat(ui): add circled question mark help button in top header rechtsbuendig

frontend/src/App.tsx

@@ -101,6 +101,7 @@ export const App: React.FC = () => {
   const [deck, setDeck] = useState<Thought[]>([]);
   const [lists, setLists] = useState<SharedList[]>([]);
   const [activeTab, setActiveTab] = useState<ActiveTab>('triage');
+  const [previousTab, setPreviousTab] = useState<ActiveTab>('triage');
   const [selectedDocId, setSelectedDocId] = useState<string | null>(null);
   const [captureFocusCount, setCaptureFocusCount] = useState(0);
   const [refreshRevision, setRefreshRevision] = useState(0);
@@ -109,6 +110,13 @@ export const App: React.FC = () => {
   const [showProfileMenu, setShowProfileMenu] = useState(false);
   const dropdownRef = useRef<HTMLDivElement | null>(null);
 
+  const handleOpenHelp = () => {
+    triggerHaptic(10);
+    setPreviousTab((prev) => (activeTab === 'help' ? prev : activeTab));
+    setActiveTab('help');
+    setShowProfileMenu(false);
+  };
+
   const handleChangeTheme = (themeId: ThemeId) => {
     triggerHaptic(10);
     applyTheme(themeId);
@@ -379,11 +387,7 @@ export const App: React.FC = () => {
                   </button>
 
                   <button
-                    onClick={() => {
-                      triggerHaptic(10);
-                      setShowProfileMenu(false);
-                      setActiveTab('help');
-                    }}
+                    onClick={handleOpenHelp}
                     className={`w-full px-3.5 py-2.5 text-left flex items-center gap-2.5 hover:bg-panel-elevated transition-colors ${
                       activeTab === 'help' ? 'text-accent font-semibold' : 'text-main'
                     }`}
@@ -424,6 +428,16 @@ export const App: React.FC = () => {
               </div>
             )}
           </div>
+
+          {/* Circled Question Mark Help Button (Rechtsbündig) */}
+          <button
+            type="button"
+            onClick={handleOpenHelp}
+            className="w-7 h-7 rounded-full border border-border hover:border-strong bg-panel hover:bg-panel-elevated text-muted hover:text-main flex items-center justify-center transition-colors flex-shrink-0"
+            title="Hilfe & Dokumentation"
+          >
+            <HelpCircle className="w-4 h-4 text-muted hover:text-main" />
+          </button>
         </div>
 
         {/* Navigation tabs attached to header */}
@@ -533,12 +547,11 @@ export const App: React.FC = () => {
               <WorkspaceView
                 initialDocId={selectedDocId}
                 onStatsChange={refreshAll}
-                onOpenHelp={() => setActiveTab('help')}
               />
             )}
 
             {activeTab === 'help' && (
-              <HelpView onBack={() => setActiveTab('workspace')} />
+              <HelpView onBack={() => setActiveTab(previousTab || 'triage')} />
             )}
 
             {activeTab === 'lists' && (