feat: implement hybrid native/python speedtest engine

- Introduce native Ookla Speedtest binary support for Gigabit connections

- Add intelligent engine detection with automatic fallback to python-cli version

- Map full JSON payload to Watched_Value3 for n8n integration

- Add Spanish (es_es) localizations and update README instructions

front/plugins/internet_speedtest/README.md

@@ -1,11 +1,33 @@
 ## Overview
 
-A simple plugin allowing for executing regular internet speed tests. 
+A plugin allowing for executing regular internet speed tests. 
 
 ### Usage
 
-- N/A
+This plugin supports two engines:
+1.  **Baseline Engine**: Uses the Python `speedtest-cli` library (default).
+2.  **Native Engine (Optimized)**: Uses the native Ookla Speedtest binary.
+
+#### Opt-in for Native Engine
+To use the native engine:
+- Provide the native `speedtest` binary in your environment: [Speedtest CLI Homepage](https://www.speedtest.net/apps/cli)
+- Map the binary to `/usr/bin/speedtest` in the container.
+- **Ensure the native speedtest binary is installed on the host at the source path.**
+
+```yaml
+volumes:
+  - /usr/bin/speedtest:/usr/bin/speedtest:ro
+```
+-  The plugin will automatically detect and use it for subsequent tests.
+
+
+### Data Mapping
+
+- **Watched_Value1** — Download Speed (Mbps).
+- **Watched_Value2** — Upload Speed (Mbps).
+- **Watched_Value3** — Full JSON payload (useful for n8n or detailed webhooks).
 
 ### Notes
 
-- N/A
+- The native binary is recommended for connections > 100 Mbps.
+- If the native binary is not detected, the plugin seamlessly falls back to the baseline library.