Feat: apply pulled changes to running HA after sync (apply_after_pull)

[askb]

Problem

The add-on pulls merged PRs into /config (git pull --rebase) but never tells Home Assistant to load them. Files on disk ≠ running config, so every merged change still needs a manual Reload Automations.

Change

New option apply_after_pull (reload | restart | off, default reload). When a sync advances HEAD (a merged PR came down) and not in dry_run, the add-on applies it via the Supervisor → core API proxy:

• reload → homeassistant.reload_all (automations, scripts, scenes, templates, input_*) — no restart
• restart → homeassistant.restart — for configuration.yaml integration or custom_components/ changes that aren't hot-reloadable
• off → previous behaviour

Enables homeassistant_api so SUPERVISOR_TOKEN is accepted by the core API proxy. Only fires on real upstream change, never on no-op runs or dry-run.

Files

• config.json — homeassistant_api: true, new option + schema list(reload|restart|off), version → 0.3.0
• rootfs/app/gitops_backup.sh — read option, ha_apply() helper, capture HEAD around the pull, apply after stash-pop
• DOCS.md, translations/en.yaml, CHANGELOG.md — document the option
• tests/self_check.sh — static wiring asserts

Validation

• jq empty config.json OK; bash -n + shellcheck clean; yamllint . clean
• bash tests/self_check.sh → OK: all self-checks passed

Notes

• reload_all does not apply configuration.yaml integration or custom_components/ changes — that's the restart option, documented, not a silent gap.
• Skipped: per-domain reload / auto-detecting reload-vs-restart from changed paths. Add if the 3-way knob proves too coarse.