Notez 0.3.11 — Nerd agent, sidebar fixes, and a smarter editor

This release welcomes Nerd as a new built-in agent for Notez, fixes the long-standing left sidebar flicker, and further improves the editor and AI experience:

• Add: Welcome Nerd, the new built-in agent for Notez, as a simple but extensible starting point for automated assistance;
• Add: Provide built-in tools for the agent, including knowledge base search, file management, and task tracking, all wired into Nerd;
• Add: Introduce a new "Nerd" tab in the right sidebar for interacting with the agent and inspecting task progress/results;
• Fix: Optimize the left sidebar rendering and state handling to eliminate long-standing flicker/jank issues during navigation;
• Upgrade: The editor and AI capabilities for more stable context understanding, completions, and conversations;
• Update: Model-related configuration and localization, adding new agent-related translations and example model references.

Thanks for using Notez — enjoy meeting Nerd, and keep the feedback coming!