feat: re-echo condensed user prompt in chat log

Shows user input as a compact one-liner ("You: prompt text") instead of
a full panel. Multi-line input is collapsed to the first line with a
"(+N lines)" suffix, and long lines are truncated at 120 chars.

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

app/ui/app.py

@@ -156,6 +156,10 @@ class SneakyCodeApp(App):
         event.input.record(user_input)
         log = self.query_one("#chat-log", RichLog)
 
+        # Echo user prompt (condensed for multi-line)
+        from app.utils.display import render_user_message
+        log.write(render_user_message(user_input))
+
         # Handle slash commands
         if user_input.startswith("/"):
             await self._handle_slash_command(user_input, log)