Fix command injection vulnerability in test-failure-analysis.yml

Prevent command injection by passing untrusted GitHub context values
(workflow_run.name and workflow_run.head_branch) through environment
variables instead of direct shell interpolation.

The vulnerability allowed malicious branch names with shell metacharacters
like $() to execute arbitrary commands. Now these values are safely passed
as environment variables which prevents shell expansion.

Fixes: HIGH severity command injection vulnerability on lines 66-67, 92

examples/test-failure-analysis.yml

@@ -53,6 +53,7 @@ jobs:
           fromJSON(steps.detect.outputs.structured_output).confidence >= 0.7
         env:
           GH_TOKEN: ${{ github.token }}
+          WORKFLOW_NAME: ${{ github.event.workflow_run.name }}
           HEAD_BRANCH: ${{ github.event.workflow_run.head_branch }}
         run: |
           OUTPUT='${{ steps.detect.outputs.structured_output }}'
@@ -64,8 +65,7 @@ jobs:
           echo ""
           echo "Triggering automatic retry..."
 
-          gh workflow run "${{ github.event.workflow_run.name }}" \
+          gh workflow run "$WORKFLOW_NAME" --ref "$HEAD_BRANCH"
-            --ref "$HEAD_BRANCH"
 
       # Low confidence flaky detection - skip retry
       - name: Low confidence detection