ci: Release Please cannot create PRs — needs Actions permissions

[forkwright]

Release Please fails with: 'GitHub Actions is not permitted to create or approve pull requests.'

Fix: Settings > Actions > General > check 'Allow GitHub Actions to create and approve pull requests'

[forkwright]

Fixed by enabling "Allow GitHub Actions to create and approve pull requests" via repo Actions workflow permissions API (PUT /repos/.../actions/permissions/workflow with can_approve_pull_request_reviews=true). Workflow permissions (contents: write, pull-requests: write) were already correct — the repo-level setting was blocking PR creation. Release Please ran successfully and opened release PR #41.