Security-Hardening (Pentest-Findings F-02 bis F-07)

- CSRF-Schutz: session-gebundenes Token in allen POST-Formularen, serverseitig
  per before_request geprueft; /nic/update ausgenommen (Basic-Auth-API)
- Brute-Force-Schutz: DB-gestuetzter Login-Lockout pro Client-IP
  (5 Fehlversuche -> 15 min), echte IP via ProxyFix/X-Forwarded-For
- SSRF: validate_plesk_url() erzwingt http(s) und blockt Link-Local/Metadata,
  Multicast und reservierte Ziele
- Session-Cookies: HttpOnly, SameSite=Lax, Secure (per Env abschaltbar)
- Security-Header: CSP, X-Frame-Options, X-Content-Type-Options, Referrer-Policy
- Generische Plesk-Fehlermeldungen (keine internen URLs im UI)
- CSS/JS nach static/ ausgelagert -> strikte CSP ohne 'unsafe-inline'
- login_attempts-Tabelle + README-Security-Abschnitt

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/static/css/app.css

@@ -0,0 +1,20 @@
+:root { --sidebar-bg: #1e2a38; --sidebar-hover: #2d3f52; }
+body { background: #f4f6f9; min-height: 100vh; }
+#sidebar {
+  width: 220px; min-width: 220px; min-height: 100vh;
+  background: var(--sidebar-bg); color: #cdd6e0;
+}
+#sidebar .brand { color: #4fc3f7; font-weight: 700; font-size: 1.1rem; }
+#sidebar .nav-link {
+  color: #b0bec5; border-radius: 6px; padding: .5rem .75rem;
+  margin-bottom: 2px; transition: background .15s;
+}
+#sidebar .nav-link:hover, #sidebar .nav-link.active {
+  background: var(--sidebar-hover); color: #fff;
+}
+#sidebar .nav-link i { width: 1.3em; }
+#sidebar hr { border-color: var(--sidebar-hover); }
+.main-content { flex: 1; padding: 2rem; min-width: 0; }
+.card { border: none; box-shadow: 0 1px 4px rgba(0,0,0,.08); }
+.badge-ip { font-family: monospace; font-size: .85em; }
+.va-baseline { vertical-align: baseline; }

app/static/css/login.css

@@ -0,0 +1,2 @@
+body { background: #1e2a38; min-height: 100vh; display: flex; align-items: center; }
+.login-card { width: 100%; max-width: 380px; }