[Hardening] F-14: Fail to Ensure Request Limits and/or Throttling by Default.

### The required feature described as a wish

**Description:** By Default, CloudStack does not enforce rate limiting or request throttling on its API endpoints. Any client with network access to the management plane can issue an unlimited number of API requests without restriction, delay, or penalty.

**Affected Components:** Management API

**Impact:** An attacker or malfunctioning client can flood the API with requests, exhausting server-side resources (e.g., DB) and causing a denial of service. The absence of throttling also enables unlimited automated authentication attempts, which compounds the risk previously described in other reports.

**Steps to Reproduce:**
- Using a custom script or a fuzzing tool, send a high volume of requests in rapid succession to any API endpoint.
- Observe that all requests are processed without any throttling, queuing delay, or rejection based on request rate.

**Recommended Remediation:** Adopt rate-limiting and throttling out-of-the-box. Return `HTTP 429` with a `Retry-After` header when a threshold is exceeded, as an attempt to slow down legit clients (attackers do not slow!)

從 CloudStack Management API 開始，透過向 API 端點傳送大量請求來重現此問題。完成標準是預設啟用請求限制和節流，過量請求會被延遲或以 HTTP 429 拒絕，且被拒絕的回應包含 Retry-After 標頭。

由索引模型根據 Issue 內容生成。