feat(ci): use COPILOT_MODEL env var for copilot targets

Copilot CLI accepts --model to set the AI model. Use a separate
COPILOT_MODEL env var (default: gpt-5-mini) for copilot-cli and
copilot-sdk targets instead of reusing GH_MODELS_MODEL.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: christso

.agentv/targets.yaml

@@ -11,13 +11,13 @@ targets:
 
   - name: copilot-cli
     provider: copilot-cli
-    model: ${{ GH_MODELS_MODEL }}
+    model: ${{ COPILOT_MODEL }}
     grader_target: default
     log_format: json
 
   - name: copilot-sdk
     provider: copilot-sdk
-    model: ${{ GH_MODELS_MODEL }}
+    model: ${{ COPILOT_MODEL }}
     grader_target: default
     log_format: json
 

.github/workflows/evals.yml

@@ -31,6 +31,7 @@ jobs:
           cat > .env <<EOF
           GH_MODELS_TOKEN=${{ secrets.GH_MODELS_TOKEN || secrets.GITHUB_TOKEN }}
           GH_MODELS_MODEL=${{ vars.GH_MODELS_MODEL || 'openai/gpt-5-mini' }}
+          COPILOT_MODEL=${{ vars.COPILOT_MODEL || 'gpt-5-mini' }}
           EOF
 
       - name: Resolve filter and threshold