Domain auf datametric360.de umgestellt (war .app)

Alle Referenzen in Doku und Code aktualisiert (REVERSE_PROXY.md,
INTERNET_ZUGRIFF_EINRICHTEN.md, COMPANION_APP_ARCHITECTURE.md, AGENTS.md,
UMSETZUNGSPLAN.md, companion-app/src/api/umgebung.ts-Kommentar). Dabei den
.app-spezifischen HSTS-Preload-Hinweis in COMPANION_APP_ARCHITECTURE.md §5.4
korrigiert - gilt für .de nicht, Force-SSL in Nginx Proxy Manager deckt das
weiterhin ab. UMSETZUNGSPLAN.md Phase 12 zusätzlich mit einem
Aktualisierungshinweis versehen (zwei-Hostnamen-Plan und pyscript-Namen dort
waren ohnehin schon überholt, jetzt klar auf REVERSE_PROXY.md/
INTERNET_ZUGRIFF_EINRICHTEN.md als maßgeblich verwiesen).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

AGENTS.md

@@ -231,7 +231,9 @@ Home Assistant (`npm run smoke`, `npm run smoke:auth`). `npm run dev` in the rep
   architecture doc, marked ÜBERHOLT. Details and open steps in section B below.
 - Frontend access: HA REST + WebSocket with a long-lived access token (no `hass` object).
 - External access: Cloudflare Tunnel + reverse proxy with a path allowlist; HA itself stays
-  unreachable. Domain **`datametric360.app`** registered (all-inkl, 2026-08-11).
+  unreachable. Domain **`datametric360.de`** registered (all-inkl, 2026-08-11; originally `.app`,
+  switched to `.de` 2026-08-28 — every doc reference updated the same day, including the note in
+  `COMPANION_APP_ARCHITECTURE.md` §5 item 4 that `.app`'s HSTS-preload advantage no longer applies).
 - Distribution: **sideload only** (license reason) — hence real Audi assets are allowed there.
 - Trip detection moves to FMM003 ignition; the pause-tolerance feature
   (`fahrten_pausenzeit_min`) is a deliberate product decision and must be preserved.
@@ -419,7 +421,7 @@ wraps the web app for iPhone; a PWA home-screen install is the accepted intermed
 
 ### B) Infrastructure / commissioning (partly waits for FMM003 hardware)
 
-- [ ] Switch `datametric360.app` nameservers at all-inkl to Cloudflare ("full setup") —
+- [ ] Switch `datametric360.de` nameservers at all-inkl to Cloudflare ("full setup") —
       prerequisite for the tunnel; domain carries nothing else, so this is consequence-free. Step-by-
       step runbook for this and everything below it now exists:
       [`homeassistant/INTERNET_ZUGRIFF_EINRICHTEN.md`](homeassistant/INTERNET_ZUGRIFF_EINRICHTEN.md)
@@ -427,7 +429,7 @@ wraps the web app for iPhone; a PWA home-screen install is the accepted intermed
       add-on UI all remain the owner's own action; nothing here can be done unattended.
 - [x] Decide hostname split — **resolved 2026-08-28: no split, one hostname is enough.** The original
       app-domain-vs-API-subdomain question assumed a served web build; distribution stayed native/
-      sideload only (never built as a web app), so `https://datametric360.app` alone covers both API
+      sideload only (never built as a web app), so `https://datametric360.de` alone covers both API
       calls and the app's own OTA bundle. See `COMPANION_APP_ARCHITECTURE.md` §5 item 4.
 - [x] Choose reverse proxy — **decided 2026-08-28: Nginx Proxy Manager**, not Traefik. See
       `COMPANION_APP_ARCHITECTURE.md` §5 item 3.