- sdk/mock.py: stream_message was async def (coroutine), must be async
generator with yield — caused TypeError on every user message
- topic_events.py: on_topic_created now skips bot-created topics
(from_user.id == bot.id); cmd_new already registers them under the
correct human user_id
- commands.py: cmd_archive now sends "Чат архивирован." confirmation
- test_topic_events.py: add bot=SimpleNamespace(id=BOT_ID) to fixture
