fix(ci): least-privilege permissions + fork-safe concurrency keys

- evals.yml / evals-periodic.yml evals jobs: explicit contents:read +
  packages:read (container-image pull) and persist-credentials:false —
  the jobs that execute PR-authored code with three provider API keys
  ran on the repo-default token grant with the token written into
  .git/config
- permissions blocks for the 4 workflows that had none (skill-docs,
  make-pdf-gate, windows-free-tests, windows-setup-e2e)
- fork-safe concurrency keys: actionlint, skill-docs, make-pdf-gate,
  windows-setup-e2e switch from head_ref to PR-number keying — a bare
  branch name carries no fork prefix, so same-name branches from two
  forks shared one group and cancelled each other's runs

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/actionlint.yml

@@ -6,11 +6,11 @@ on:
     branches: [main]
   pull_request:
 
-# Cancel superseded runs for the same branch (matches evals.yml,
-# windows-free-tests.yml, etc.). head_ref is set on pull_request; ref_name is
-# the fallback for push so a rapid push series doesn't pile up stale lint runs.
+# PR-number keyed (run_id fallback for push): a bare branch name carries no
+# fork prefix, so same-name branches from two forks would share one group and
+# cancel each other's runs (same rationale as free-tests.yml).
 concurrency:
-  group: actionlint-${{ github.head_ref || github.ref_name }}
+  group: actionlint-${{ github.event.pull_request.number || github.run_id }}
   cancel-in-progress: true
 
 # Lint needs nothing from the token; the job runs a third-party image with