feat(agent): add Gemini 3.1 support and improve model routing

docs/content/docs/cuabench/guide/fundamentals/agent-traces.mdx

@@ -96,21 +96,17 @@ Opens an interactive viewer showing:
 - Action details and metadata
 - Agent reasoning (if available)
 
-### View All Traces in a Run
+### View Agent Trajectories from a Run
 
 ```bash
-# View all task traces in a grid
-cb trace grid <run_id>
+# Open agent trajectories in the cua.ai trajectory viewer
+cb trace traj <run_id>
 
 # Example
-cb trace grid 96d41b51
+cb trace traj 96d41b51
 ```
 
-Shows a grid view of all task traces in the run, useful for:
-
-- Comparing agent performance across variants
-- Quickly identifying failures
-- Reviewing oracle solutions
+Zips and serves the cua-agent trajectory recordings from the run artifacts folder, then opens [cua.ai/trajectory-viewer](https://cua.ai/trajectory-viewer). For runs with multiple tasks, an index page is shown so you can open each session individually.
 
 ## Recording Custom Events
 

docs/content/docs/cuabench/reference/cli-reference.mdx

@@ -251,10 +251,10 @@ View and manage trace datasets.
 cb trace <action> <id>
 ```
 
-| Command              | Description                                                   |
-| -------------------- | ------------------------------------------------------------- |
-| `cb trace view <id>` | View a single trace in browser (accepts run_id or session_id) |
-| `cb trace grid <id>` | View all traces in a run as a grid (accepts run_id)           |
+| Command              | Description                                                          |
+| -------------------- | -------------------------------------------------------------------- |
+| `cb trace view <id>` | View a single trace in browser (accepts run_id or session_id)        |
+| `cb trace traj <id>` | View agent trajectories from a run in cua.ai/trajectory-viewer       |
 
 ## Dataset Commands