docs(adr): ADR-0016 — notfallhandbuch stays lab-internal, no mirror

Standing exception to ADR-0001 (everything is push-mirrored to Gitea). The
handbook necessarily maps the infrastructure, the backup locations and where the
keys are kept; mirroring it onto the internet-facing host that is itself one of
the covered failure cases would hand a post-compromise attacker their next step.
Confidentiality over availability, with a local clone closing the availability
gap. Records the rejected alternatives so the question does not reopen.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

STATUS.md

@@ -45,7 +45,7 @@ Verteilung: M1 7 · M2 19 · M4 2 · M5 4
 
 _none active_
 
-## ADRs (15)
+## ADRs (16)
 
 | ADR | Status | Title |
 |---|---|---|
@@ -64,6 +64,7 @@ _none active_
 | [0013](docs/adr/0013-gruppenregeln-kanonisch-mit-pruefung.md) | accepted | ADR-0013: Gruppenregeln kanonisch im management-Repo, Komponenten zeigen und werden geprüft |
 | [0014](docs/adr/0014-wikijs-loest-docusaurus-ab.md) | accepted | 0014 — Wiki.js löst Docusaurus ab: abgeschottete Betriebs-/Anwenderdoku, docs-as-code |
 | [0015](docs/adr/0015-wiki-git-storage-ueber-gitea-kanonisieren.md) | accepted | 0015 — Wiki.js Git-Storage: Inhalt fließt Cluster→Gitea→kanonisiert nach git.lab |
+| [0016](docs/adr/0016-notfallhandbuch-nicht-spiegeln.md) | accepted | 0016 — Das Notfallhandbuch bleibt lab-intern und wird nicht gespiegelt |
 
 ## Open AARs (2)