feat: echo MiniApp commands to chat for user visibility

When a command is sent from the MiniApp (source=webapp), echo it
to the Telegram chat before processing so the user can confirm
what was sent.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pkg/agent/loop.go

@@ -242,6 +242,16 @@ func (al *AgentLoop) Run(ctx context.Context) error {
 			continue
 		}
 
+		// Echo commands sent from the Mini App so the user can see what was sent.
+		if msg.Metadata["source"] == "webapp" && msg.Content != "" {
+			al.bus.PublishOutbound(bus.OutboundMessage{
+				Channel:         msg.Channel,
+				ChatID:          msg.ChatID,
+				Content:         "via MiniApp: " + msg.Content,
+				SkipPlaceholder: true,
+			})
+		}
+
 		// Fast path: handle slash commands immediately without blocking the LLM worker.
 		if response, handled := al.handleCommand(ctx, msg); handled {
 			if response != "" {