fix(ui): 积分价格保留两位小数，不再四舍五入成整数

frontend/src/credits.js

@@ -1,12 +1,13 @@
 // Credit display helpers. Credits and model prices are stored server-side as
-// integer 积分 (points) — the single unit across the whole app. These helpers
-// only format for display; they do NOT convert units.
-/** Round to an integer 积分 value. */
+// 积分 (points) — the single unit across the whole app. Prices can be fractional
+// (0.11 积分/s), so keep two decimals instead of rounding them away. These
+// helpers only format for display; they do NOT convert units.
+/** Round to a 积分 value with at most 2 decimals. */
 export function points(value) {
-  return Math.round(Number(value || 0))
+  return Math.round(Number(value || 0) * 100) / 100
 }
 
 /** "<n> 积分" label with thousands separators. */
 export function pointsLabel(value) {
-  return points(value).toLocaleString('en-US') + ' 积分'
+  return points(value).toLocaleString('en-US', { maximumFractionDigits: 2 }) + ' 积分'
 }