feat(mcp): delete tasks, create task lists and lists, agent badge; export/import settings category

New MCP tools delete_task (tasks:write), create_task_list (tasks:write) and create_list
(lists:write); list_task_lists now returns the board columns so agents know the valid
kanbanStatus values. Task deletion is a shared helper (deleteTask) for REST and MCP.

Tasks and list items get agent_mark (migration 12): "created" when an agent adds them via MCP,
"edited" when an agent changes them; a change by the user clears it. The new AgentBadge shows
"KI" / "KI geändert" in task rows, Kanban cards, the task detail, the inbox and lists.

Settings: export and import move out of "Webhooks, KI-Agenten & Export" into their own
category "Export & Import". Docs, help, README and changelog updated; v0.29.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/features/triage/TriageDeck.tsx

@@ -25,6 +25,7 @@ import {
 import { SharedList, Thought } from '../../lib/types';
 import { addDays, formatDue } from '../../lib/due';
 import { api, triggerHaptic } from '../../lib/api';
+import { AgentBadge } from '../../components/AgentBadge';
 
 interface TriageDeckProps {
   deck: Thought[];
@@ -158,6 +159,7 @@ const SwipeableQueueItem: React.FC<SwipeableQueueItemProps> = ({
               <Mic className="w-2.5 h-2.5" /> Diktat
             </span>
           )}
+          <AgentBadge mark={item.agentMark} />
         </div>
 
         {/* Desktop quick buttons (hidden on mobile so queue items are clean & easy to tap/swipe) */}
@@ -521,6 +523,7 @@ export const TriageDeck: React.FC<TriageDeckProps> = ({
             <div className="flex items-center gap-1.5">
               {priorityBadge(nextCard.priority)}
               {sourceBadge(nextCard.source)}
+              <AgentBadge mark={nextCard.agentMark} />
             </div>
             <p className="text-sm text-muted line-clamp-2">{nextCard.content}</p>
             <div className="text-[11px] text-faint">Nächster Quick Dump…</div>
@@ -590,6 +593,7 @@ export const TriageDeck: React.FC<TriageDeckProps> = ({
               <div className="flex items-center gap-1.5">
                 {priorityBadge(activeCard.priority)}
                 {sourceBadge(activeCard.source)}
+                <AgentBadge mark={activeCard.agentMark} />
               </div>
               <div
                 className="flex items-center gap-2"