Fix chat widget UI and allow attachment-only messages

- Allow sending messages with only attachments (no text required)
- Change "Chat Ativo" header to just "Chat"
- Replace Headphones icon with MessageCircle for own messages
- Replace PhoneOff icon with XCircle for end chat button

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/chat/chat-widget.tsx

@@ -22,10 +22,9 @@ import {
   X,
   Minimize2,
   User,
-  Headphones,
   ChevronDown,
   WifiOff,
-  PhoneOff,
+  XCircle,
   Paperclip,
   FileText,
   Image as ImageIcon,
@@ -428,7 +427,7 @@ export function ChatWidget() {
               </div>
               <div>
                 <div className="flex items-center gap-2">
-                  <p className="text-sm font-semibold text-slate-900">Chat Ativo</p>
+                  <p className="text-sm font-semibold text-slate-900">Chat</p>
                   {/* Indicador online/offline */}
                   {liveChat?.hasMachine && (
                     machineOnline ? (
@@ -464,7 +463,7 @@ export function ChatWidget() {
                 {isEndingChat ? (
                   <Spinner className="size-3.5" />
                 ) : (
-                  <PhoneOff className="size-3.5" />
+                  <XCircle className="size-3.5" />
                 )}
                 <span className="hidden sm:inline">Encerrar</span>
               </Button>
@@ -548,7 +547,7 @@ export function ChatWidget() {
                           isOwn ? "bg-black text-white" : "bg-slate-200 text-slate-600"
                         )}
                       >
-                        {isOwn ? <Headphones className="size-3.5" /> : <User className="size-3.5" />}
+                        {isOwn ? <MessageCircle className="size-3.5" /> : <User className="size-3.5" />}
                       </div>
                       <div
                         className={cn(