fix(cli): slash command UX — ignore bare /, fix gateway connection check

- Submitting bare "/" no longer shows "Unknown command format: /" — input
  is ignored silently so autocomplete can guide discovery instead
- Gateway command handler no longer requires a conversationId before
  emitting — the socket connection check alone is sufficient; missing
  conversationId caused false "Not connected" errors on fresh sessions

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

packages/cli/src/tui/app.tsx

@@ -117,12 +117,12 @@ export function TuiApp({
 
   const handleGatewayCommand = useCallback(
     (parsed: ParsedCommand) => {
-      if (!socket.socketRef.current?.connected || !socket.conversationId) {
+      if (!socket.socketRef.current?.connected) {
         socket.addSystemMessage('Not connected to gateway. Command cannot be executed.');
         return;
       }
       socket.socketRef.current.emit('command:execute', {
-        conversationId: socket.conversationId,
+        conversationId: socket.conversationId ?? '',
         command: parsed.command,
         args: parsed.args ?? undefined,
       });

packages/cli/src/tui/components/input-bar.tsx

@@ -59,8 +59,7 @@ export function InputBar({
       if (trimmed.startsWith('/')) {
         const parsed = parseSlashCommand(trimmed);
         if (!parsed) {
-          onSystemMessage?.(`Unknown command format: ${trimmed}`);
-          setInput('');
+          // Bare "/" or malformed — ignore silently (autocomplete handles discovery)
           return;
         }
         const def = commandRegistry.find(parsed.command);