fix: restore Expand/Minimize button in AI panel + dynamic width, note thumbnail SVG placeholder with emoji/letter

memento-note/components/contextual-ai-chat.tsx

@@ -516,7 +516,8 @@ export function ContextualAIChat({
 
   return (
     <aside className={cn(
-      'border-l border-border/40 bg-background flex flex-col h-full w-full flex-shrink-0 z-10 transition-all duration-300',
+      'border-l border-border/40 bg-background flex flex-col h-full flex-shrink-0 z-10 transition-all duration-300',
+      expanded ? 'w-[560px]' : 'w-[360px]',
       className,
     )}>
 
@@ -553,6 +554,16 @@ export function ContextualAIChat({
                 <Wand2 className="h-3.5 w-3.5" />
               </Button>
             )}
+            <Button
+              variant="ghost" size="icon"
+              className="h-7 w-7 text-muted-foreground hover:text-foreground"
+              onClick={() => setExpanded(e => !e)}
+              title={expanded ? t('ai.shrinkPanel') : t('ai.expandPanel')}
+            >
+              {expanded
+                ? <Minimize2 className="h-3.5 w-3.5" />
+                : <Maximize2 className="h-3.5 w-3.5" />}
+            </Button>
             <Button variant="ghost" size="icon" onClick={onClose} className="h-7 w-7 text-muted-foreground hover:text-foreground">
               <X className="h-3.5 w-3.5" />
             </Button>