Add device tag support to Prometheus metrics

- Add 'tag' label to all device metric descriptors
- Update exportWithTags helper to create separate metric series per tag
- Update all device export functions (UAP, USW, UDM, USG, UXG, PDU, UBB, UCI) to include tags
- Update all label arrays (VAP, Radio, Port, etc.) to include tag label
- Devices with multiple tags create multiple metric series (one per tag)
- Devices without tags export with tag=""

Requires unpoller/unifi#92

scripts/README_API_DUMP.md

@@ -0,0 +1,42 @@
+# Saving UniFi API Output
+
+Ways to save API responses and explorer output for discovery or debugging.
+
+## Single endpoint → file
+
+Redirect `unpoller -j "other <path>"` to a file:
+
+```bash
+unpoller -c up.conf -j "other /api/s/default/stat/device" > device.json
+unpoller -c up.conf -j "other /api/s/default/stat/sta"     > clients.json
+```
+
+Use `jq` to inspect: `jq . device.json`
+
+## Bulk dump → directory
+
+Use the dump script to request many known endpoints and save each to a JSON file:
+
+```bash
+./scripts/dump_unifi_api.sh -c up.conf -s default -o ./api_dump
+```
+
+Output goes to `./api_dump` by default. See `./scripts/dump_unifi_api.sh -h` for options.
+
+Note: some endpoints (e.g. `sitedpi`, `stadpi`) require POST with a body; the script only issues GETs, so those may fail or return errors. You can still inspect the saved responses.
+
+## Saving the API explorer UI
+
+If you're using the developer UI (e.g. [developer.ui.com](https://developer.ui.com) or another API explorer) and want to save the **list of endpoints and their details**:
+
+1. **OpenAPI / Swagger spec**  
+   Open DevTools → **Network**, (re)load the explorer, and look for requests to `openapi.json`, `swagger.json`, or similar. Right‑click the response → **Copy** → **Save as**, or use **Save all as HAR** and extract the spec from the HAR.
+
+2. **Save page**  
+   Use **File → Save As** (HTML) or **Print → Save as PDF** to capture the visible explorer structure. This won’t persist dynamically loaded data unless the page embeds it.
+
+3. **Export**  
+   If the explorer has an **Export** or **Download** button (e.g. for OpenAPI YAML/JSON), use that to save the full spec.
+
+4. **Community specs**  
+   Community OpenAPI specs for the UniFi API exist (e.g. [ubiquiti-community/unifi-api](https://github.com/ubiquiti-community/unifi-api), [ringods/unifi-api-spec](https://github.com/ringods/unifi-api-spec)). Clone or download those repos to get machine‑readable API definitions.