Adds create/edit/delete of playbooks from the UI (admin only), so a homelab
user without a git workflow can author automation in-app. A new always-present
writable local source "steward-local" (/data/ansible/playbooks, env-overridable,
created on first save) is editable alongside operator local-dir sources; the
bundled and git sources stay read-only (git is GitOps, clobbered on pull).
sources.py: write_playbook / delete_playbook (traversal-guarded, .yml/.yaml
only) + validate_playbook_yaml (YAML + play-list check) + is_editable_source.
routes.py: /playbooks/new, /edit, /save, /delete (admin). Browse gains a
"New playbook" button and per-playbook + view-page Edit/Delete for editable
sources. Plain textarea editor with save-time YAML validation. Unit tests for
write/delete/guard/validate.
Task #579 — completes milestone #37 (Ansible automation).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
