agent: Allow customizing temperature by provider/model (#30033)

Adds a new `agent.model_parameters` setting that allows the user to
specify a custom temperature for a provider AND/OR model:

```json5
    "model_parameters": [
      // To set parameters for all requests to OpenAI models:
      {
        "provider": "openai",
        "temperature": 0.5
      },
      // To set parameters for all requests in general:
      {
        "temperature": 0
      },
      // To set parameters for a specific provider and model:
      {
        "provider": "zed.dev",
        "model": "claude-3-7-sonnet-latest",
        "temperature": 1.0
      }
    ],
```

Release Notes:

- agent: Allow customizing temperature by provider/model

---------

Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>
Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/worktree/src/worktree.rs

@@ -3871,7 +3871,7 @@ impl BackgroundScanner {
             Some(ancestor_dot_git)
         });
 
-        log::info!("containing git repository: {containing_git_repository:?}");
+        log::trace!("containing git repository: {containing_git_repository:?}");
 
         let (scan_job_tx, scan_job_rx) = channel::unbounded();
         {