cc-copilot 0.18.1

Patch release for the prompt navigation update.\n\n- Fix Sticky Prompt positioning for short conversations, long conversations, and exact prompt-boundary scroll positions.\n- Keep the sticky prompt aligned with the selected prompt after keyboard or mouse navigation.\n- Keep slash-style provider model IDs on router backends unless the user explicitly prefixes another backend.\n\nPyPI: https://pypi.org/project/cc-copilot/0.18.1/