Implement all vendor integrations, WAN graphs, and FortiGate health panel

- Wire up 26 vendor providers: Atlassian Statuspage API, Status.io, Instatus,
  AWS RSS feeds, Apple/Google JSON feeds, M365 Graph API, and synthetic checks
- Add 11 new providers: AWS, Cloudflare, SmartPass, School Dismissal Manager,
  SherpaDesk, Classkick, ClassDojo, Savvas, Study Island, Promethean, RAZ-Kids
- Rename Local Infrastructure → Internet (TCP check to 8.8.8.8:53)
- Add WAN throughput graph section: dual-link canvas graphs (Crown Castle +
  Comcast) polling FortiGate REST API every 30s with 30-min rolling history
- Add FortiGate health card: uptime, CPU %, memory % from FortiOS API
- Add /api/throughput and /api/fortigate-health endpoints
- Add README with setup instructions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/providers/promethean.js

@@ -0,0 +1,17 @@
+export const name = "Promethean";
+export const url = "https://www.prometheanworld.com/";
+
+// No cloud features in use — panels run in standalone mode. No public status
+// page exists. Synthetic check confirms basic web reachability only.
+const PROBE_URL = "https://www.prometheanworld.com/";
+
+export async function checkStatus() {
+  const res = await fetch(PROBE_URL, { method: "HEAD" });
+
+  return {
+    name,
+    status: "operational",
+    message: `Site responding (HTTP ${res.status}).`,
+    lastUpdated: new Date().toISOString(),
+  };
+}