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

tests/cli/test_cli_input.py

@@ -145,3 +145,29 @@ def test_response_renderable_without_metadata_keeps_markdown_path():
     renderable = commands._response_renderable(help_text, render_markdown=True)
 
     assert renderable.__class__.__name__ == "Markdown"
+
+
+def test_stream_renderer_stop_for_input_stops_spinner():
+    """stop_for_input should stop the active spinner to avoid prompt_toolkit conflicts."""
+    spinner = MagicMock()
+    mock_console = MagicMock()
+    mock_console.status.return_value = spinner
+
+    # Create renderer with mocked console
+    with patch.object(stream_mod, "_make_console", return_value=mock_console):
+        renderer = stream_mod.StreamRenderer(show_spinner=True)
+        
+        # Verify spinner started
+        spinner.start.assert_called_once()
+        
+        # Stop for input
+        renderer.stop_for_input()
+        
+        # Verify spinner stopped
+        spinner.stop.assert_called_once()
+
+
+def test_make_console_uses_force_terminal():
+    """Console should be created with force_terminal=True for proper ANSI handling."""
+    console = stream_mod._make_console()
+    assert console._force_terminal is True