fix: resolve TypeScript type-check errors

- Add cacheHitRate to ProxyMetricsService, handler, and router schema
- Fix StatCard to support string values and purple accent
- Fix duplicate tabs keys in i18n translations (EN/ZH/RU)
- Add missing cacheStatus translations across all languages

.planning/phases/02-code-review-command/02-REVIEW-summary.md

@@ -0,0 +1,58 @@
+Here is the code review report for the Token Usage Counter feature.
+
+## Summary
+
+The review found 2 critical security issues and 2 warnings. The overall architecture is solid, but the security issues must be addressed before this code is merged.
+
+## Critical Issues
+
+### CR-01: SQL Injection Vulnerability in TokenUsageRepo filter methods
+
+**Issue:** `buildAccountFilter` concatenates `accountId` directly into raw SQL.
+**Fix:** Use parameterized queries.
+
+```typescript
+function buildAccountFilter(accountId?: string): { sql: string; params: string[] } {
+  return accountId ? { sql: `AND account_id = ?`, params: [accountId] } : { sql: '', params: [] };
+}
+```
+
+### CR-02: Missing validation in TokenUsageRepo queries
+
+**Issue:** `buildDateFilter` directly interpolates `start` and `end` arguments.
+**Fix:** Ensure parameters are passed safely using parameterized queries.
+
+```typescript
+function buildDateFilter(start?: number, end?: number): { sql: string; params: number[] } {
+  const conditions: string[] = [];
+  const params: number[] = [];
+  if (start !== undefined) {
+    conditions.push(`timestamp >= ?`);
+    params.push(start);
+  }
+  if (end !== undefined) {
+    conditions.push(`timestamp <= ?`);
+    params.push(end);
+  }
+  return {
+    sql: conditions.length > 0 ? `AND ${conditions.join(' AND ')}` : '',
+    params,
+  };
+}
+```
+
+## Warnings
+
+### WR-01: Synchronous Database Writing in ProxyService
+
+**Issue:** `recordUsage` calls a synchronous database insertion on every proxy request, which can cause severe performance bottlenecks under load.
+**Fix:** Consider making the usage recording asynchronous (fire-and-forget), using an asynchronous database driver, or implementing a batching mechanism.
+
+### WR-02: Missing Unsubscribe / Cleanup in React Query hooks
+
+**Issue:** The usage dashboard queries lack an auto-refresh mechanism.
+**Fix:** Add `refetchInterval: 10000` to the query configuration.
+
+## Info
+
+Consider using CSS variables for the Recharts colors instead of hardcoded hex values to support light/dark mode better.