feat: add @goose off commands to disable AI

Added support for turning AI off after enabling it:

useChatEngine.ts:
- Added detection for @goose off/disable/stop/quiet/sleep commands
- When AI is enabled and user sends @goose off, AI gets disabled
- Message is added to chat without triggering AI response
- Console logging shows when AI is disabled

EnhancedMentionPopover.tsx:
- Added multiple @goose command options in autocomplete:
  - @goose (enable AI)
  - @goose off (disable AI)
  - @goose stop (stop AI)
  - @goose quiet (make AI quiet)
- Updated icons to show different emojis for off commands (🦆💤)
- All goose commands get green styling and 'Mention' action hint

Now users can:
1. Start DM (AI disabled by default)
2. Send @goose to enable AI
3. Send @goose off to disable AI again
4. Autocomplete shows all available @goose commands

ui/desktop/src/components/EnhancedMentionPopover.tsx

@@ -84,19 +84,44 @@ const EnhancedMentionPopover = forwardRef<
   const mentionItems = useMemo((): MentionItem[] => {
     const items: MentionItem[] = [];
     
-    // Add "goose" as a special mention for AI reinitialization
-    const gooseScore = fuzzyMatch(query, 'goose');
-    if (gooseScore > 0 || !query.trim()) {
-      items.push({
-        id: 'goose',
-        type: 'friend', // Use friend type for consistent styling
-        name: 'goose',
-        displayText: 'goose',
-        secondaryText: 'Reinitialize AI assistance',
-        userId: 'goose',
-        matchScore: gooseScore + 100, // Highest priority for goose
-      });
-    }
+    // Add "goose" commands as special mentions for AI control
+    const gooseCommands = [
+      {
+        command: 'goose',
+        description: 'Enable AI assistance',
+        emoji: '🦆'
+      },
+      {
+        command: 'goose off',
+        description: 'Disable AI assistance',
+        emoji: '🦆💤'
+      },
+      {
+        command: 'goose stop',
+        description: 'Stop AI assistance',
+        emoji: '🦆🛑'
+      },
+      {
+        command: 'goose quiet',
+        description: 'Make AI quiet',
+        emoji: '🦆🤫'
+      }
+    ];
+
+    gooseCommands.forEach(({ command, description, emoji }) => {
+      const score = fuzzyMatch(query, command);
+      if (score > 0 || !query.trim()) {
+        items.push({
+          id: command,
+          type: 'friend', // Use friend type for consistent styling
+          name: command,
+          displayText: command,
+          secondaryText: description,
+          userId: command,
+          matchScore: score + 100, // Highest priority for goose commands
+        });
+      }
+    });
     
     // Add friends (prioritize if connected)
     if (isConnected && friends.length > 0) {
@@ -251,9 +276,12 @@ const EnhancedMentionPopover = forwardRef<
                   {/* Icon */}
                   <div className="flex-shrink-0">
                     {item.type === 'friend' ? (
-                      item.userId === 'goose' ? (
+                      item.userId?.startsWith('goose') ? (
                         <div className="w-6 h-6 bg-green-500 rounded-full flex items-center justify-center">
-                          <span className="text-white text-xs font-bold">🦆</span>
+                          <span className="text-white text-xs">
+                            {item.userId === 'goose' ? '🦆' : 
+                             item.userId.includes('off') || item.userId.includes('stop') || item.userId.includes('quiet') ? '🦆💤' : '🦆'}
+                          </span>
                         </div>
                       ) : (
                         <div className="w-6 h-6 bg-blue-500 rounded-full flex items-center justify-center">
@@ -286,11 +314,11 @@ const EnhancedMentionPopover = forwardRef<
                     <div className={`text-xs px-2 py-1 rounded ${
                       index === selectedIndex 
                         ? 'bg-text-on-accent/20 text-text-on-accent' 
-                        : item.userId === 'goose' 
+                        : item.userId?.startsWith('goose')
                           ? 'bg-green-100 text-green-600' 
                           : 'bg-blue-100 text-blue-600'
                     }`}>
-                      {item.userId === 'goose' ? 'Mention' : 'Invite'}
+                      {item.userId?.startsWith('goose') ? 'Mention' : 'Invite'}
                     </div>
                   )}
                 </div>

ui/desktop/src/hooks/useChatEngine.ts

@@ -185,8 +185,33 @@ export const useChatEngine = ({
         : '';
       const containsGooseMention = /@goose\b/i.test(messageText);
       
-      // If @goose is mentioned, enable AI for this session
-      if (containsGooseMention && !aiEnabled) {
+      // Check for @goose off/disable/stop commands
+      const gooseOffPattern = /@goose\s+(off|disable|stop|quiet|sleep)\b/i;
+      const isGooseOffCommand = gooseOffPattern.test(messageText);
+      
+      // If @goose off is mentioned, disable AI for this session
+      if (isGooseOffCommand && aiEnabled) {
+        console.log('🦆💤 @goose off mentioned - disabling AI for session:', {
+          sessionId: chat.sessionId,
+          messageId: message.id,
+          contentPreview: messageText.substring(0, 50) + '...'
+        });
+        
+        // Update the chat to disable AI
+        setChat((prevChat: ChatType) => ({ ...prevChat, aiEnabled: false }));
+        
+        // Add the message to the chat without triggering AI response
+        setMessages(prevMessages => [...prevMessages, message]);
+        
+        // Store in history if it's a user message
+        storeMessageInHistory(message);
+        
+        // Return a promise that resolves immediately (to match originalAppend's interface)
+        return Promise.resolve();
+      }
+      
+      // If @goose is mentioned (but not an off command), enable AI for this session
+      if (containsGooseMention && !isGooseOffCommand && !aiEnabled) {
         console.log('🦆 @goose mentioned - enabling AI for session:', {
           sessionId: chat.sessionId,
           messageId: message.id,