fix: Scroll chat to bottom immediately on user message send

frontend/src/components/agent/PromptBar.vue

@@ -579,10 +579,9 @@ function handleSessionChange(sessionId: string) {
 
 function handleSubmit(text: string) {
   messages.push({ id: ++idCounter, role: 'user', content: text, status: 'sent' })
+  scrollToBottom()
   emit('submit', text)
-  // Send text as input to the agent's terminal PTY
   agentTerminal.sendPrompt(text)
-  // Real response will arrive via transcript-update WebSocket
 }
 
 function handleMic() {
@@ -599,9 +598,9 @@ function handleTranscriptDone(text: string) {
   if (!text.trim()) return
 
   messages.push({ id: ++idCounter, role: 'user', content: text, status: 'sent' })
+  scrollToBottom()
   emit('submit', text)
   agentTerminal.sendPrompt(text)
-  // Real response will arrive via transcript-update WebSocket
 }
 
 function toggleSettings() {