docs: draft the German ChurchTools forum post on structure-as-code

[2000game]

Adds docs/forum/2026-08-strukturen-als-code.md — the German forum post that has been the goal behind the recent docs work.

This is a draft in the repo, not a published post. It carries a pre-publish checklist rather than assuming it is ready to go.

What the post does

Aimed at a general ChurchTools-admin audience, in German with Du-Ansprache:

1. Why — five questions clicking cannot answer (audit trail, repeatability for the next campus, a safe rehearsal, drift detection, previewing a change).
2. Show me — the same zero-id config and real ct plan output as the README.
3. Scope — what is managed, and the two boundaries stated plainly: people and memberships are never touched, and only explicitly declared or adopted resources are visible at all.
4. Guardrails — never deletes, backup before writes, typed confirmation on protected environments, host-bound state files, tokens out of the repo.
5. Dev → prod — the rehearsal workflow, including that the plan header surfaces a version skew between instances before you promote.
6. Two findings worth sharing — that rights reach a group through two independent layers (and the per-group UI only shows one), and that person-status grants are the instance-wide lever. Both stated in the deliberately non-technical form, claiming only what was verified live.
7. Questions — to the community, and one to ChurchTools about the "preliminary" permission / dynamic-group endpoints we depend on.

Deliberately separate from #91

#91 wants a technical post that extracts precise answers about dataId: -1, GET /statuses, and which permission domains are really writable. This post wants to start a conversation. Combining them would weaken both, so the draft says so explicitly and leaves #91 open.

Open decision, flagged in the draft

eqrm/ct-cli is private. The post is written so it works with no repo link at all; the checklist puts the choice (post without a link / open the repo first / link a short public description) in front of a human rather than resolving it silently.

https://claude.ai/code/session_01KPxjSEkqMiU7WE3vg6C3am