feat(lotto): 브리핑 컴포넌트 + CSS

src/pages/lotto/components/briefing/pricing.js

@@ -0,0 +1,23 @@
+const IN_PER_M = 3.00;
+const OUT_PER_M = 15.00;
+const CACHE_READ_PER_M = 0.30;
+const CACHE_WRITE_PER_M = 3.75;
+
+export function estimateCost({ tokens_input = 0, tokens_output = 0, cache_read = 0, cache_write = 0 }) {
+    const usd =
+        (tokens_input / 1_000_000) * IN_PER_M +
+        (tokens_output / 1_000_000) * OUT_PER_M +
+        (cache_read / 1_000_000) * CACHE_READ_PER_M +
+        (cache_write / 1_000_000) * CACHE_WRITE_PER_M;
+    return usd;
+}
+
+export function fmtUsd(usd) {
+    if (usd < 0.01) return `$${usd.toFixed(4)}`;
+    return `$${usd.toFixed(3)}`;
+}
+
+export function fmtTokens(n) {
+    if (n >= 1000) return `${(n / 1000).toFixed(1)}K`;
+    return String(n);
+}