Add type picker for entity creation, icon grid filter, and serial port placeholder

- Replace inline type selectors with pre-modal type picker grid for devices,
  color strip sources, and value sources
- Add filterable search to icon grid when items > 9 (no auto-focus on touch)
- Show disabled (grayed-out) filtered items instead of hiding them
- Responsive grid columns (2-5 cols based on viewport width)
- Add "Select a port..." placeholder to serial port dropdown
- Update en/ru/zh locales with new keys

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

server/src/wled_controller/templates/modals/add-device.html

@@ -20,7 +20,7 @@
                 <hr class="modal-divider">
             </div>
             <form id="add-device-form">
-                <div class="form-group">
+                <div class="form-group" id="device-type-group">
                     <div class="label-row">
                         <label for="device-type" data-i18n="device.type">Device Type:</label>
                         <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>