feat: hover rename/delete icons in treeview, resizable tree and sidebar panels

frontend/src/components/ai/SessionList.tsx

@@ -52,6 +52,7 @@ function TreeItem({
   onContextMenu: (e: React.MouseEvent, type: 'session' | 'folder' | 'root', id: string | null) => void;
   onDragSession: (sessionId: string) => void;
   onDropToFolder: (folderId: string | null) => void;
+  onDelete: (id: string, type: 'session' | 'folder') => void;
 }) {
   const [expanded, setExpanded] = useState(true);
   const [isDragOver, setIsDragOver] = useState(false);
@@ -94,6 +95,12 @@ function TreeItem({
             <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 7v10a2 2 0 002 2h14a2 2 0 002-2V9a2 2 0 00-2-2h-6l-2-2H5a2 2 0 00-2 2z" />
           </svg>
           <span className="flex-1 truncate">{node.folder!.name}</span>
+              <button onClick={(e) => { e.stopPropagation(); onContextMenu(e.nativeEvent, 'folder', node.folder!.id); }} className="opacity-0 group-hover:opacity-100 text-secondary-400 hover:text-primary-600 p-0.5" title="Umbenennen">
+                <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M11 5H6a2 2 0 00-2 2v11a2 2 0 002 2h11a2 2 0 002-2v-5m-1.414-9.414a2 2 0 112.828 2.828L11.828 15H9v-2.828l8.586-8.586z" /></svg>
+              </button>
+              <button onClick={(e) => { e.stopPropagation(); onDelete(node.folder!.id, 'folder'); }} className="opacity-0 group-hover:opacity-100 text-secondary-400 hover:text-red-600 p-0.5" title="Löschen">
+                <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" /></svg>
+              </button>
         </div>
       )}
 
@@ -124,6 +131,12 @@ function TreeItem({
               <span className={clsx('flex-1 truncate', activeSessionId === session.id && 'font-bold text-primary-700')}>
                 {session.title}
               </span>
+              <button onClick={(e) => { e.stopPropagation(); onContextMenu(e.nativeEvent, 'session', session.id); }} className="opacity-0 group-hover:opacity-100 text-secondary-400 hover:text-primary-600 p-0.5" title="Umbenennen">
+                <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M11 5H6a2 2 0 00-2 2v11a2 2 0 002 2h11a2 2 0 002-2v-5m-1.414-9.414a2 2 0 112.828 2.828L11.828 15H9v-2.828l8.586-8.586z" /></svg>
+              </button>
+              <button onClick={(e) => { e.stopPropagation(); onDelete(session.id, 'session'); }} className="opacity-0 group-hover:opacity-100 text-secondary-400 hover:text-red-600 p-0.5" title="Löschen">
+                <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" /></svg>
+              </button>
             </div>
           ))}
         </div>
@@ -154,6 +167,7 @@ function TreeItem({
           onContextMenu={onContextMenu}
           onDragSession={onDragSession}
           onDropToFolder={onDropToFolder}
+          onDelete={onDelete}
         />
       ))}
     </div>
@@ -313,6 +327,7 @@ export function SessionList({ activeSessionId, onSelectSession, isSidebar, class
             onContextMenu={handleContextMenu}
             onDragSession={setDragSessionId}
             onDropToFolder={handleDropToFolder}
+            onDelete={handleDelete}
           />
         ))}
       </div>

frontend/src/components/layout/AISidebar.tsx

@@ -1,5 +1,6 @@
 import React, { useState, useEffect } from 'react';
 import { ChatWindow } from '@/components/ai/ChatWindow';
+import { ResizablePanel } from '@/components/ui/ResizablePanel';
 import { createSession, fetchSessions } from '@/api/ai';
 import { useUIStore } from '@/store/uiStore';
 
@@ -9,7 +10,6 @@ export function AISidebar() {
   const [loading, setLoading] = useState(true);
 
   useEffect(() => {
-    // Find or create a sidebar session
     (async () => {
       try {
         const sessions = await fetchSessions(true);
@@ -28,7 +28,14 @@ export function AISidebar() {
   }, []);
 
   return (
-    <div className="w-80 flex-shrink-0 border-l border-secondary-200 bg-white flex flex-col h-full">
+    <ResizablePanel
+      initialWidth={320}
+      minWidth={240}
+      maxWidth={600}
+      className="border-l border-secondary-200 bg-white"
+      data-testid="ai-sidebar-pane"
+    >
+      <div className="h-full flex flex-col">
         <div className="h-12 flex items-center justify-between px-3 border-b border-secondary-200">
           <span className="text-sm font-medium text-secondary-700">KI Assistent</span>
           <button
@@ -51,5 +58,6 @@ export function AISidebar() {
           )}
         </div>
       </div>
+    </ResizablePanel>
   );
 }

frontend/src/pages/AIAssistant.tsx

@@ -1,6 +1,7 @@
 import React, { useState, useEffect } from 'react';
 import { SessionList } from '@/components/ai/SessionList';
 import { ChatWindow } from '@/components/ai/ChatWindow';
+import { ResizablePanel } from '@/components/ui/ResizablePanel';
 import { usePluginToolbarStore } from '@/store/pluginToolbarStore';
 import { fetchAgents, type AIAgent } from '@/api/ai';
 
@@ -69,8 +70,16 @@ export function AIAssistantPage() {
   return (
     <div className="flex h-full" data-testid="ai-assistant-page">
       {/* Desktop: two-pane layout */}
-      <div className="hidden md:flex w-72 flex-shrink-0 border-r border-secondary-200 bg-white flex-col">
-        <SessionList key={refreshKey} activeSessionId={activeSessionId} onSelectSession={setActiveSessionId} className="flex-1" />
+      <div className="hidden md:flex">
+        <ResizablePanel
+          initialWidth={288}
+          minWidth={200}
+          maxWidth={500}
+          className="border-r border-secondary-200 bg-white"
+          data-testid="ai-session-pane"
+        >
+          <SessionList key={refreshKey} activeSessionId={activeSessionId} onSelectSession={setActiveSessionId} className="h-full" />
+        </ResizablePanel>
       </div>
       <div className="hidden md:flex flex-1 flex-col">
         {activeSessionId ? <ChatWindow sessionId={activeSessionId} agentId={selectedAgentId} className="flex-1" /> : (