feat(workspace): enhance todo view switcher and add note-level collapsible cards in folder_note mode

frontend/src/features/workspace/WorkspaceView.tsx

@@ -1240,9 +1240,12 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                   </p>
                 </div>
 
-                <div className="flex items-center gap-2">
+                <div className="flex flex-wrap items-center gap-2">
                   {/* View Grouping Selector */}
-                  <div className="flex rounded-btn bg-panel p-0.5 border border-border">
+                  <div className="flex items-center rounded-btn bg-panel p-0.5 border border-border shadow-xs">
+                    <span className="text-[10px] uppercase font-bold text-faint px-1.5 hidden sm:inline">
+                      Ansicht:
+                    </span>
                     <button
                       type="button"
                       onClick={() => {
@@ -1254,11 +1257,12 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                           ? 'bg-panel-elevated text-main shadow-xs'
                           : 'text-muted hover:text-main'
                       }`}
-                      title="Gruppieren nach Ordner und Notiz"
+                      title="Erst nach Ordner, dann nach Notiz gruppieren"
                     >
                       <Folder className="w-3 h-3 text-accent" />
                       <span>+</span>
                       <FileText className="w-3 h-3 text-accent" />
+                      <span>Ordner & Notiz</span>
                     </button>
                     <button
                       type="button"
@@ -1488,25 +1492,48 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                           <div className="p-2 space-y-3">
                             {Array.from(docGroupsMap.values()).map(({ doc, items: docItems }) => {
                               const docOpenCount = docItems.filter((i) => !i.checked).length;
+                              const isDocCollapsed = collapsedTodoNotes.has(doc.id);
                               return (
                                 <div
                                   key={doc.id}
                                   className="border border-border/60 rounded-btn p-2 bg-panel-elevated/30 space-y-1.5"
                                 >
                                   <div className="flex items-center justify-between pb-1 border-b border-border/40">
+                                    <div
+                                      onClick={() => {
+                                        setCollapsedTodoNotes((prev) => {
+                                          const next = new Set(prev);
+                                          if (next.has(doc.id)) next.delete(doc.id);
+                                          else next.add(doc.id);
+                                          return next;
+                                        });
+                                      }}
+                                      className="flex items-center gap-1.5 text-xs font-semibold text-main hover:text-accent cursor-pointer select-none"
+                                    >
+                                      {isDocCollapsed ? (
+                                        <ChevronRight className="w-3 h-3 text-faint" />
+                                      ) : (
+                                        <ChevronDown className="w-3 h-3 text-accent" />
+                                      )}
+                                      <span>{doc.icon || '📝'}</span>
+                                      <span>{doc.title}</span>
+                                      <span className="badge-neutral text-[9px] font-mono">
+                                        {docOpenCount} offen
+                                      </span>
+                                    </div>
+
                                     <button
                                       type="button"
                                       onClick={() => handleJumpToDocBlock(doc.id)}
-                                      className="flex items-center gap-1.5 text-xs font-semibold text-accent hover:underline cursor-pointer"
+                                      className="text-[10px] text-accent hover:underline px-1.5 py-0.5 rounded-btn hover:bg-canvas cursor-pointer flex items-center gap-1"
+                                      title="Notiz öffnen"
                                     >
-                                      <span>{doc.icon || '📝'}</span>
+                                      <span>Notiz öffnen</span>
-                                      <span>{doc.title}</span>
+                                      <ExternalLink className="w-2.5 h-2.5" />
-                                      <span className="badge-neutral text-[9px]">
-                                        {docOpenCount} offen
-                                      </span>
                                     </button>
                                   </div>
 
+                                  {!isDocCollapsed && (
                                     <div className="space-y-0.5">
                                       {docItems.map((item) => (
                                         <div
@@ -1558,6 +1585,7 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
                                         </div>
                                       ))}
                                     </div>
+                                  )}
                                 </div>
                               );
                             })}