i18n: language picker in the bottom-right corner

Replaces the EN/ES/RU buttons in the Visual Presets dock with a picker
that scales to many languages: a globe button with the current code
next to the POWER UP chip, opening a list of languages named in their
own language with their codes, the current one first and checked. A
search field appears past 8 languages. Keyboard: arrows, Home/End,
Enter/Space, Esc, type-ahead; keys stay in the list while it is open.
Choosing a language still asks before dropping unsaved work, then
reloads. Phones get the globe alone and a full-width sheet; the layout
uses logical properties for right-to-left languages.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/ui/templates/command-dock.html

@@ -10,8 +10,6 @@
         <span class="panel-title" data-i18n-runtime><span class="dock-label-icon dock-label-icon-presets" aria-hidden="true"></span>VISUAL PRESETS</span>
         <span class="panel-divider"></span>
       </button>
-      <!-- Language selector: buttons are rendered by applicationShell _initLocaleSelector(), one per shipped locale. -->
-      <div class="dock-locale-switch" role="group" data-i18n-aria-label aria-label="Language"></div>
       <div id="control-panel-popover" class="dock-popover-content">
       <button class="dock-pin-btn" data-pin-target="control-panel" type="button" aria-label="Pin visual presets" aria-pressed="false" title="Keep visual presets open" data-i18n-aria-label data-i18n-title><img src="/pin.svg" alt="" /></button>
       <div id="style-buttons" class="button-grid">