feat: implement tiered billing expression evaluation and related functionality

- Added support for tiered billing expressions in the billing system.
- Introduced new types and functions for handling billing expressions, including caching and execution.
- Updated existing billing logic to accommodate tiered billing scenarios.
- Enhanced request handling to support incoming billing expression requests.
- Added tests for tiered billing functionality to ensure correctness.

web/src/components/table/usage-logs/UsageLogsColumnDefs.jsx

@@ -377,6 +377,43 @@ function renderCompactDetailSummary(summarySegments) {
   );
 }
 
+function buildTieredBillingSegments(other, t) {
+  const segments = [
+    { text: `${t('阶梯计费')}`, tone: 'primary' },
+  ];
+
+  if (other.matched_tier) {
+    segments.push({
+      text: `${t('命中档位')}: ${other.matched_tier}`,
+      tone: 'secondary',
+    });
+  }
+
+  const groupRatio = other.group_ratio;
+  if (groupRatio !== undefined && groupRatio !== null) {
+    segments.push({
+      text: `${t('分组')} ${formatRatio(groupRatio)}x`,
+      tone: 'secondary',
+    });
+  }
+
+  if (other.crossed_tier) {
+    segments.push({
+      text: `${t('跨阶梯')}: ${t('是')}`,
+      tone: 'secondary',
+    });
+  }
+
+  if (other.actual_quota_after_group !== undefined) {
+    segments.push({
+      text: `${t('实际额度')}: ${other.actual_quota_after_group}`,
+      tone: 'secondary',
+    });
+  }
+
+  return { segments };
+}
+
 function getUsageLogDetailSummary(record, text, billingDisplayMode, t) {
   const other = getLogOther(record.other);
 
@@ -414,6 +451,10 @@ function getUsageLogDetailSummary(record, text, billingDisplayMode, t) {
     };
   }
 
+  if (other?.billing_mode === 'tiered_expr') {
+    return buildTieredBillingSegments(other, t);
+  }
+
   return {
     segments: other?.claude
       ? renderModelPriceSimple(