feat: Add Ollama keep_alive param to control how long models stay loaded

[davidmigloz]

https://github.com/ollama/ollama/releases/tag/v0.1.23

keepAlive: How long (in minutes) to keep the model loaded in memory.

• If set to a positive duration (e.g. 20), the model will stay loaded for the provided duration.
• If set to a negative duration (e.g. -1), the model will stay loaded indefinitely.
• If set to 0, the model will be unloaded immediately once finished.
• If not set, the model will stay loaded for 5 minutes by default