refactor(honeybar): HONEYBAR_ORIGIN statt INKNOTE_HONEYBAR_ORIGIN

Dieselben Namen wie in Aether. Die Leiste gehoert keiner App, sie ist ueberall
dieselbe Sache — dann soll sie auch ueberall gleich heissen. Ein zweiter Name
fuer dieselbe Einstellung ist eine Fehlerquelle beim Umziehen und beim Suchen.

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

CHANGELOG.md

@@ -21,7 +21,7 @@ a rebuild is not bit-identical.
 **Added**
 - **A strip along the top that leads to the other apps.** It is served by
   HoneyOS, so what it looks like and which apps it lists are settled there —
-  InkNote only says where to find it. `INKNOTE_HONEYBAR_ORIGIN` in the `.env`
+  InkNote only says where to find it. `HONEYBAR_ORIGIN` in the `.env`
   switches it on, empty leaves everything exactly as before.
 - **`GET /api/public/config`** hands out that origin, and the key that goes with
   it when HoneyOS lives on a different site. Runtime, not build time: an image