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/package-lock.json

@@ -9,6 +9,7 @@
       "version": "1.0.0",
       "dependencies": {
         "cors": "^2.8.5",
+        "dotenv": "^16.4.7",
         "express": "^4.21.2"
       }
     },
@@ -174,6 +175,18 @@
         "npm": "1.2.8000 || >= 1.4.16"
       }
     },
+    "node_modules/dotenv": {
+      "version": "16.6.1",
+      "resolved": "https://registry.npmjs.org/dotenv/-/dotenv-16.6.1.tgz",
+      "integrity": "sha512-uBq4egWHTcTt33a72vpSG0z3HnPuIl6NqYcTrKEg2azoEyl2hpW0zqlxysq2pK9HlDIHyHyakeYaYnSAwd8bow==",
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      },
+      "funding": {
+        "url": "https://dotenvx.com"
+      }
+    },
     "node_modules/dunder-proto": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/dunder-proto/-/dunder-proto-1.0.1.tgz",