security(ci): add least-privilege permissions block to e2e-wheel workflow

e2e-wheel.yml was the only workflow missing a top-level permissions: block
(added during cross-OS work after PR #624 hardened the rest), so it ran with
default broad GITHUB_TOKEN scopes -> OpenSSF Scorecard Token-Permissions = 0.
Add 'permissions: contents: read' to match the other 7 workflows. CHANGELOG
W24 entry.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.github/workflows/e2e-wheel.yml

@@ -23,6 +23,11 @@ on:
       - "src/**"
   workflow_dispatch:
 
+# Least-privilege token (Scorecard Token-Permissions). This workflow only
+# reads the repo to build + smoke-test the wheel; it needs no write scopes.
+permissions:
+  contents: read
+
 jobs:
   e2e-wheel:
     name: e2e-wheel (${{ matrix.os }})