chore: use pull request based approach for changelog updates

[DeepDiver1975]

Replace the direct push to master with a pull request based approach.

Changes

• Drop DEPLOYMENT_SSH_KEY and direct git push in favour of peter-evans/create-pull-request
• Use a GitHub App token (TRANSLATION_APP_ID / TRANSLATION_APP_PRIVATE_KEY) so the created pull request triggers CI
• Fixed branch name chore/changelog-update with delete-branch: true — existing pull requests are reused across runs; a fresh one opens after merge
• Pin actions/checkout to SHA
• Add permissions: {} at workflow and job level (restrict GITHUB_TOKEN to no permissions)
• persist-credentials: false on checkout as required by peter-evans/create-pull-request

🤖 Generated with Claude Code

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.