Support ollama keep_alive parameter in plugin settings

[dorianbrown]

Is your feature request related to a problem? Please describe.

Currently by default ollama keeps the model in memory until 5 minutes has passed. This consumes RAM/VRAM, and can impact the performance of other programs being run after using obsidian-copilot. It would be nice if we could configure the timeout to be something shorter (or longer if wanted).

Describe the solution you'd like

Provide a keep_alive option in the ollama configuration section of the plugin.