ci(docs): authenticate documentation workflow via GitHub App token

[MaxDall]

The Documentation workflow regenerates docs/supported_publishers.md and commits it back to master. Since master is protected, the default GITHUB_TOKEN cannot push and the run fails with GH006.

This adds an actions/create-github-app-token@v1 step that mints a short-lived token for the fundus-docs-bot GitHub App and passes it to actions/checkout, so the auto-commit step pushes as the App. All other steps are unchanged.

Required before merge

• Repo secrets DOCS_BOT_APP_ID and DOCS_BOT_PRIVATE_KEY
• The App added to the master ruleset bypass list (App bypass requires a Ruleset, not classic branch protection)

The App is scoped to Contents: write on this repo only, and the token is minted fresh per run (~1h lifetime).

Verified

A workflow_dispatch run against this branch (run 32954562637) completed successfully: the App token was minted, actions/checkout used it, and git-auto-commit-action pushed the regenerated docs back to the branch. The temporary publisher change used to produce a docs diff, and the resulting bot commit, have both been removed — the PR is now the workflow change only.

Not covered by that test: the run checked out this branch, so the protected-branch bypass on master is exercised for the first time only after merge.

[addie9800]

Looks good to me 👍