feat: add streaming channel support with automatic fallback

Provider layer: add chat_stream / chat_stream_with_retry to all providers
(base fallback, litellm, custom, azure, codex). Refactor shared kwargs
building in each provider.

Channel layer: BaseChannel gains send_delta (no-op) and supports_streaming
(checks config + method override). ChannelManager routes _stream_delta /
_stream_end to send_delta, skips _streamed final messages.

AgentLoop._dispatch builds bus-backed on_stream/on_stream_end callbacks
when _wants_stream metadata is set. Non-streaming path unchanged.

CLI: clean up spinner ANSI workarounds, simplify commands.py flow.
Made-with: Cursor

nanobot/channels/manager.py

@@ -130,7 +130,12 @@ class ChannelManager:
                 channel = self.channels.get(msg.channel)
                 if channel:
                     try:
-                        await channel.send(msg)
+                        if msg.metadata.get("_stream_delta") or msg.metadata.get("_stream_end"):
+                            await channel.send_delta(msg.chat_id, msg.content, msg.metadata)
+                        elif msg.metadata.get("_streamed"):
+                            pass
+                        else:
+                            await channel.send(msg)
                     except Exception as e:
                         logger.error("Error sending to {}: {}", msg.channel, e)
                 else: