ollama: Resolve context window size via API

[bennetbo]

Previously we were guessing the context window size here:

zed/crates/ollama/src/ollama.rs

Line 22 in 8c3f09e

fn get_max_tokens(name: &str) -> u64 {

This is inaccurate and must be updated manually. This PR ensures that we extract the context window size from the request in the same way that the Ollama CLI does when running ollama show <model-name> (Relevant code is here)

The format looks like this:

{
  "model_info": {
    "general.architecture": "llama",
    "llama.context_length": 132000
  }
}

Once this PR is merged we could technically remove the old code

zed/crates/ollama/src/ollama.rs

Line 22 in 8c3f09e

fn get_max_tokens(name: &str) -> u64 {

I decided to keep it for now, as it is unclear if the necessary fields are available via the API on older Ollama versions.

Release Notes:

• Fixed an issue where Ollama models would use the wrong context window size