refactor: replace inline SVG exchange icons with local image files (#1224)

web/public/exchange-icons/aster.svg

@@ -0,0 +1,12 @@
+<svg viewBox="0 0 32 32" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <defs>
+    <linearGradient id="aster_grad" x1="18.94" y1="0" x2="12.64" y2="32.05" gradientUnits="userSpaceOnUse">
+      <stop stop-color="#F4D5B1"/>
+      <stop offset="1" stop-color="#FFD29F"/>
+    </linearGradient>
+  </defs>
+  <path d="M9.13 30.44L9.88 26.99C10.72 23.14 7.78 19.5 3.82 19.5H0.39C1.47 24.34 4.75 28.35 9.13 30.44Z" fill="url(#aster_grad)"/>
+  <path d="M10.64 31.07C12.33 31.67 14.16 32 16.06 32C23.72 32 30.13 26.65 31.73 19.5H21.25C16.52 19.5 12.44 22.78 11.44 27.38L10.64 31.07Z" fill="url(#aster_grad)"/>
+  <path d="M32 17.9C32.08 17.28 32.12 16.64 32.12 16C32.12 7.6 25.63 0.72 17.38 0.05L15.13 10.41C14.29 14.26 17.24 17.9 21.19 17.9H32Z" fill="url(#aster_grad)"/>
+  <path d="M15.75 0C7.02 0.17 0 7.27 0 16C0 16.64 0.04 17.28 0.11 17.9H3.76C8.49 17.9 12.57 14.62 13.57 10.01L15.75 0Z" fill="url(#aster_grad)"/>
+</svg>

web/public/exchange-icons/bitget.svg

@@ -0,0 +1,5 @@
+<svg viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <rect width="40" height="40" rx="8.71" fill="#00f0ff"/>
+  <path d="M18.46 15.77h7.47l7.64 7.59c0.5 0.49 0.5 1.3 0.01 1.79L23.78 35h-7.69l2.33-2.26 8.54-8.49-8.43-8.49" fill="#1b1b1b"/>
+  <path d="M21.53 24.23h-7.47l-7.64-7.59c-0.5-0.49-0.5-1.3-0.01-1.79L16.21 5h7.69l-2.33 2.26-8.54 8.49 8.43 8.49" fill="#1b1b1b"/>
+</svg>

web/public/exchange-icons/okx.svg

@@ -0,0 +1,8 @@
+<svg viewBox="0 0 40 40" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <rect width="40" height="40" rx="8" fill="#000"/>
+  <rect x="7" y="7" width="8" height="8" rx="1" fill="#fff"/>
+  <rect x="16" y="16" width="8" height="8" rx="1" fill="#fff"/>
+  <rect x="25" y="7" width="8" height="8" rx="1" fill="#fff"/>
+  <rect x="7" y="25" width="8" height="8" rx="1" fill="#fff"/>
+  <rect x="25" y="25" width="8" height="8" rx="1" fill="#fff"/>
+</svg>