refactor: use de gruyter ci

frontend/static/degruyter-icons/Simple/Large-32px/SVG/Action/Calendar/Calendar-Add-LG.svg

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="32px" height="32px" viewBox="0 0 32 32" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <title>🧩 Icons/Simple/Action/32px/Calendar/Calendar-Add-LG</title>
+    <g id="🧩-Icons/Simple/Action/32px/Calendar/Calendar-Add-LG" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
+        <path d="M12,2 L12,4 L20,4 L20,2 L26,2 L26,4 L30,4 L30,28 L21.290196,28.001282 C19.8801103,29.2452454 18.0281963,30 16,30 C13.9718037,30 12.1198897,29.2452454 10.709804,28.001282 L2,28 L2,4 L6,4 L6,2 L12,2 Z M16,16 C12.6862915,16 10,18.6862915 10,22 C10,25.3137085 12.6862915,28 16,28 C19.3137085,28 22,25.3137085 22,22 C22,18.6862915 19.3137085,16 16,16 Z M6,6 L4,6 L4,26 L9.07092854,26.0011597 C8.71258488,25.3819299 8.43486585,24.7102108 8.25212715,24.0003581 L6,24 L6,22 L8,22 L8,22 C8,21.3096328 8.08744724,20.63969 8.25186923,20.000644 L6,20 L6,18 L9,18 L9.00048842,18.1231128 C9.44597218,17.320532 10.0254861,16.602619 10.708799,15.9996048 L6,16 L6,14 L26,14 L26,16 L21.291201,15.9996048 C21.9750792,16.6031179 22.5549867,17.3217201 23.0006171,18.1251051 L23,18 L26,18 L26,20 L23.7481308,20.000644 C23.9125528,20.63969 24,21.3096328 24,22 C24,23.4576273 23.6101668,24.8242042 22.9290715,26.0011597 L28,26 L28,6 L26,6 L26,8 L20,8 L20,6 L12,6 L12,8 L6,8 L6,6 Z M17,18 L17,21 L20,21 L20,23 L17,23 L17,26 L15,26 L15,23 L12,23 L12,21 L15,21 L15,18 L17,18 Z M26,10 L26,12 L10,12 L10,10 L26,10 Z M24,4 L22,4 L22,6 L24,6 L24,4 Z M10,4 L8,4 L8,6 L10,6 L10,4 Z" id="Primary" fill="#000000"></path>
+    </g>
+</svg>