fix(cli): prevent spinner ANSI escape codes from being printed verbatim

Fixes #2591

The "nanobot is thinking..." spinner was printing ANSI escape codes
literally in some terminals, causing garbled output like:
  ?[2K?[32m⠧?[0m ?[2mnanobot is thinking...?[0m

Root causes:
1. Console created without force_terminal=True, so Rich couldn't
   reliably detect terminal capabilities
2. Spinner continued running during user input prompt, conflicting
   with prompt_toolkit

Changes:
- Set force_terminal=True in _make_console() for proper ANSI handling
- Add stop_for_input() method to StreamRenderer
- Call stop_for_input() before reading user input in interactive mode
- Add tests for the new functionality

nanobot/cli/commands.py

@@ -1004,6 +1004,9 @@ def agent(
                 while True:
                     try:
                         _flush_pending_tty_input()
+                        # Stop spinner before user input to avoid prompt_toolkit conflicts
+                        if renderer:
+                            renderer.stop_for_input()
                         user_input = await _read_interactive_input_async()
                         command = user_input.strip()
                         if not command:

nanobot/cli/stream.py

@@ -18,7 +18,7 @@ from nanobot import __logo__
 
 
 def _make_console() -> Console:
-    return Console(file=sys.stdout)
+    return Console(file=sys.stdout, force_terminal=True)
 
 
 class ThinkingSpinner:
@@ -120,6 +120,10 @@ class StreamRenderer:
         else:
             _make_console().print()
 
+    def stop_for_input(self) -> None:
+        """Stop spinner before user input to avoid prompt_toolkit conflicts."""
+        self._stop_spinner()
+
     async def close(self) -> None:
         """Stop spinner/live without rendering a final streamed round."""
         if self._live: