Gemini CLI: Unified Auto Mode and New External Editor Support

Gemini CLI v0.44.0 consolidates the previously separate "Auto (Gemini 3)" and "Auto (Gemini 2.5)" model options into a single unified Auto mode that dynamically routes requests based on task complexity and the user's release channel. The /model manage dialog now shows one "Auto" entry whose description updates in real time to reflect which specific models are active. Additionally, Sublime Text and Emacs Client join the list of natively supported external editors, and misconfigured editor settings now produce clear, actionable error messages instead of cryptic failures.