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>

newtab.html

@@ -223,7 +223,7 @@
     <div class="panel-footer">
       <div class="about-block">
         <div class="about-logo" data-i18n="about.title">⬡ HELLION NEWTAB</div>
-        <div class="about-version">Version 2.0.1 · by Hellion Online Media</div>
+        <div class="about-version">Version 2.1.0 · by Hellion Online Media</div>
 
         <div class="about-links">
           <a href="https://hellion-media.de/impressum" target="_blank" class="about-link">