fix: add explicit permissions to skill-eval workflow (CodeQL alert)

Co-authored-by: zdrawku <11193764+zdrawku@users.noreply.github.com>

Author: Copilot

.github/workflows/skill-eval.yml

@@ -6,6 +6,10 @@ on:
       - 'skills/**'
       - 'evals/**'
 
+permissions:
+  contents: read
+  pull-requests: write
+
 jobs:
   eval:
     runs-on: ubuntu-latest