feat(release): Version auf v2.1.0 bumpen — Calculator Upgrade

Alle 3 Manifests, newtab.html, data.js, app.js auf 2.1.0.
CHANGELOG-Eintrag mit allen 6 neuen Calculator-Modi.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

manifest.json

@@ -2,7 +2,7 @@
   "manifest_version": 3,
   "name": "__MSG_extName__",
   "default_locale": "en",
-  "version": "2.0.1",
+  "version": "2.1.0",
   "description": "__MSG_extDesc__",
   "author": "Hellion Online Media - Florian Wathling",
   "homepage_url": "https://hellion-media.de",