feat(cli): one-line startup banner showing model name (#400)

Display a concise startup banner with model name when running in interactive TTY mode.

agentmain.py

@@ -265,6 +265,14 @@ if __name__ == '__main__':
         try: import readline
         except Exception: pass
         agent.inc_out = True
+        if sys.stdout.isatty():
+            try: model = agent.get_llm_name(model=True) or '?'
+            except Exception: model = '?'
+            try:
+                sys.stdout.write(f'\x1b[92m✦\x1b[0m \x1b[1mGenericAgent\x1b[0m '
+                                 f'\x1b[90m· cli · model:\x1b[0m {model}\n')
+                sys.stdout.flush()
+            except Exception: pass
         while True:
             q = input('> ').strip()
             if not q: continue