Add remote API support for UniFi Site Manager

- Add remote API mode with automatic controller discovery
- Discover consoles via /v1/hosts endpoint
- Auto-discover sites for each console via integration API
- Use console name from hosts response as site name override for Cloud Gateways
- Support both config-level and per-controller remote mode
- Add example configs for YAML, JSON, and TOML formats
- Remote API uses api.ui.com with X-API-Key authentication
- Automatically discovers all consoles when remote=true and remote_api_key is set

This enables monitoring multiple UniFi Cloud Gateways through a single
API key without requiring direct network access to each controller.

examples/remote_api_example.json

@@ -0,0 +1,42 @@
+{
+  "poller": {
+    "debug": false,
+    "quiet": false
+  },
+  "unifi": {
+    "remote": true,
+    "remote_api_key": "YOUR_API_KEY_HERE",
+    "defaults": {
+      "save_sites": true,
+      "save_dpi": true,
+      "save_events": true,
+      "save_alarms": true,
+      "save_anomalies": true,
+      "save_ids": true,
+      "save_traffic": true,
+      "save_rogue": true,
+      "save_syslog": true,
+      "save_protect_logs": false,
+      "verify_ssl": true
+    }
+  },
+  "prometheus": {
+    "disable": false,
+    "http_listen": "0.0.0.0:9130",
+    "namespace": "unpoller",
+    "report_errors": false,
+    "dead_ports": false
+  },
+  "influxdb": {
+    "disable": true
+  },
+  "webserver": {
+    "enable": false
+  },
+  "datadog": {
+    "enable": false
+  },
+  "loki": {
+    "disable": true
+  }
+}