[Hardening] F-12: Absence of Per-Account or Per-User Source CIDR Allowlist.

### The required feature described as a wish

**Description:** CloudStack does not provide a built-in mechanism to restrict per-account or per-user access to a defined set of source IP addresses or CIDR ranges. Any IP address that can reach the management plane can attempt to authenticate as any account.

**Affected Components:** Management UI / API

**Impact:** Without source IP allowlisting, a stolen API key or compromised credential set can be used from any network location globally. There is no network-level control to limit the blast radius of a credential compromise. High-privilege service accounts are particularly at risk, as they can be accessed from unexpected locations without raising any flags.

**Steps to Reproduce:**
- This finding is not directly reproducible since it reflects the absence of a control.

**Recommended Remediation:** Implement a per-account or per-user source CIDR allowlist field in the data model. Requests originating from IPs outside the defined allowlist should be rejected and logged as a security event.

Das Issue identifiziert die Management UI/API, das Account- oder User-Datenmodell, Prüfungen der Request-Quell-IP und das Logging von Security-Events, nennt aber keine Dateien oder Tests. Beginne damit, diese Einstiegspunkte zu finden und die Authentifizierung und Autorisierung für API-Requests nachzuverfolgen. Der Abschluss sollte eine definierte CIDR-Richtlinie pro Account oder User, die Ablehnung außerhalb der Richtlinie sowie geloggte Security-Events mit Abdeckung des relevanten Verhaltens enthalten.

Vom Indexierungsmodell aus dem Issue-Text verfasst.