fix(proxy): isolate image-proxy rate limiter

lib/security/rate-limiter.ts

@@ -80,6 +80,9 @@ export const rateLimiters = {
   // 文件上传接口：每分钟60次请求（独立于通用API限流）
   upload: new RateLimiter(60000, 60),
 
+  // 图片代理接口：每分钟3000次请求（图片列表/画布高频加载）
+  imageProxy: new RateLimiter(60000, 3000),
+
   // 高频只读接口（首页/画布轮询）：每分钟1200次请求
   uiPolling: new RateLimiter(60000, 1200),
 

proxy.ts

@@ -77,6 +77,20 @@ export async function proxy(request: NextRequest) {
         { status: 429 }
       );
     }
+  } else if (pathname === "/api/image-proxy" && request.method === "GET") {
+    const imageProxyRateLimit = checkRateLimit(request, rateLimiters.imageProxy);
+    if (!imageProxyRateLimit.allowed) {
+      const retryAfter = Math.max(1, Math.ceil((imageProxyRateLimit.resetTime - Date.now()) / 1000));
+      console.warn(`[Security] Image proxy rate limit exceeded for IP: ${clientIP}`, {
+        pathname,
+        method: request.method,
+        resetTime: new Date(imageProxyRateLimit.resetTime).toISOString(),
+      });
+      return NextResponse.json(
+        { error: "Too many image proxy requests", retryAfter },
+        { status: 429, headers: { "Retry-After": String(retryAfter) } }
+      );
+    }
   } else if (pathname === "/api/files/upload" && request.method === "POST") {
     const token = await resolveToken();
     const userId =